diff --git a/cli/buildengine.ts b/cli/buildengine.ts
index 2f82456e7271..95ee1d5e0d6e 100644
--- a/cli/buildengine.ts
+++ b/cli/buildengine.ts
@@ -411,7 +411,7 @@ function updateCodalBuildAsync() {
         .then(
             () => /v\d+/.test(cs.gittag) ? Promise.resolve() : codalGitAsync("pull"),
             e =>
-                codalGitAsync("checkout", "master")
+                codalGitAsync("checkout", "master") // leave as master
                     .then(() => codalGitAsync("pull")))
         .then(() => codalGitAsync("checkout", cs.gittag))
 }
diff --git a/cli/cli.ts b/cli/cli.ts
index 20fce52b0bc5..8eb0c570d6d3 100644
--- a/cli/cli.ts
+++ b/cli/cli.ts
@@ -251,49 +251,6 @@ function searchAsync(...query: string[]) {
         })
 }
 
-function pkginfoAsync(repopath: string) {
-    let parsed = pxt.github.parseRepoId(repopath)
-    if (!parsed) {
-        console.log('Unknown repo');
-        return Promise.resolve();
-    }
-
-    const pkgInfo = (cfg: pxt.PackageConfig, tag?: string) => {
-        pxt.log(`name: ${cfg.name}`)
-        pxt.log(`description: ${cfg.description}`)
-        if (pxt.appTarget.appTheme)
-            pxt.log(`shareable url: ${pxt.appTarget.appTheme.embedUrl}#pub:gh/${parsed.fullName}${tag ? "#" + tag : ""}`)
-    }
-
-    return pxt.packagesConfigAsync()
-        .then(config => {
-            const status = pxt.github.repoStatus(parsed, config);
-            pxt.log(`github org: ${parsed.owner}`);
-            if (parsed.tag) pxt.log(`github tag: ${parsed.tag}`);
-            pxt.log(`package status: ${status == pxt.github.GitRepoStatus.Approved ? "approved" : status == pxt.github.GitRepoStatus.Banned ? "banned" : "neutral"}`)
-            if (parsed.tag)
-                return pxt.github.downloadPackageAsync(repopath, config)
-                    .then(pkg => {
-                        let cfg: pxt.PackageConfig = JSON.parse(pkg.files[pxt.CONFIG_NAME])
-                        pkgInfo(cfg, parsed.tag)
-                        pxt.debug(`size: ${JSON.stringify(pkg.files).length}`)
-                    })
-
-            return pxt.github.pkgConfigAsync(parsed.fullName)
-                .then(cfg => {
-                    pkgInfo(cfg)
-                    return pxt.github.listRefsAsync(repopath)
-                        .then(tags => {
-                            pxt.log("tags: " + tags.join(", "))
-                            return pxt.github.listRefsAsync(repopath, "heads")
-                        })
-                        .then(heads => {
-                            pxt.log("branches: " + heads.join(", "))
-                        })
-                })
-        })
-}
-
 export function pokeRepoAsync(parsed: commandParser.ParsedCommand): Promise<void> {
     const repo = parsed.args[0];
 
@@ -450,18 +407,18 @@ function ciAsync() {
         fs.writeFileSync(npmrc, cfg)
     }
 
-    const latest = branch == "master" ? "latest" : "git-" + branch
-    // upload locs on build on master
-    const masterOrReleaseBranchRx = /^(master|v\d+\.\d+\.\d+)$/;
-    const apiStringBranchRx = pxt.appTarget.uploadApiStringsBranchRx
-        ? new RegExp(pxt.appTarget.uploadApiStringsBranchRx)
-        : masterOrReleaseBranchRx;
+    const defaultBranch = pxt.github.isDefaultBranch(branch)
+    const latest = defaultBranch ? "latest" : "git-" + branch
+    // upload locs on build on default or releases
+    const apiStringBranchRx: (t: string) => boolean = ((t:string) => new RegExp(pxt.appTarget.uploadApiStringsBranchRx).test(t))
+        ? ((t: string) => new RegExp(pxt.appTarget.uploadApiStringsBranchRx).test(t))
+        : ((t: string) => pxt.github.isDefaultOrReleaseBranch(t));
     const uploadDocs = !pullRequest
         && !!pxt.appTarget.uploadDocs
-        && masterOrReleaseBranchRx.test(branch);
+        && pxt.github.isDefaultOrReleaseBranch(branch);
     const uploadApiStrings = !pullRequest
         && (!!pxt.appTarget.uploadDocs || pxt.appTarget.uploadApiStringsBranchRx)
-        && apiStringBranchRx.test(branch);
+        && apiStringBranchRx(branch);
 
     pxt.log(`tag: ${tag}`);
     pxt.log(`branch: ${branch}`);
@@ -482,7 +439,7 @@ function ciAsync() {
             .then(isTaggedCommit => {
                 pxt.log(`is tagged commit: ${isTaggedCommit}`);
                 let p = npmPublishAsync();
-                if (branch === "master" && isTaggedCommit) {
+                if (defaultBranch && isTaggedCommit) {
                     if (uploadDocs)
                         p = p
                             .then(() => buildWebStringsAsync())
@@ -1664,14 +1621,14 @@ function ciBuildInfo(): CiBuildInfo {
 
         pxt.log(`event name: ${eventName}`);
 
-        // PR: not on master or not a release number
+        // PR: not on default or not a release number
         return {
             ci: "githubactions",
             branch,
             tag,
             commit,
             commitUrl: "https://github.com/" + repoSlug + "/commits/" + commit,
-            pullRequest: !(branch == "master" || /^v\d+\.\d+\.\d+$/.test(tag))
+            pullRequest: !pxt.github.isDefaultOrReleaseBranch(branch)
         }
     }
 }
@@ -5429,32 +5386,6 @@ function writeProjects(prjs: SavedProject[], outDir: string): string[] {
     return dirs;
 }
 
-function cherryPickAsync(parsed: commandParser.ParsedCommand) {
-    const commit = parsed.args[0];
-    const name = parsed.flags["name"] || commit.slice(0, 7);
-    let majorVersion = parseInt(pxtVersion().split('.')[0]);
-    const gitAsync = (args: string[]) => nodeutil.spawnAsync({
-        cmd: "git",
-        args
-    })
-
-    let branches: string[] = [];
-    for (let i = majorVersion - 1; i >= 0; --i) branches.push("v" + i);
-    pxt.log(`cherry picking ${commit} into ${branches.join(', ')}`)
-
-    let p = gitAsync(["pull"]);
-    branches.forEach(branch => {
-        const pr = `cp/${branch}${name}`;
-        p = p.then(() => gitAsync(["checkout", branch]))
-            .then(() => gitAsync(["pull"]))
-            .then(() => gitAsync(["checkout", "-b", pr]))
-            .then(() => gitAsync(["cherry-pick", commit]))
-            .then(() => gitAsync(["push", "--set-upstream", "origin", pr]));
-    })
-
-    return p.catch(() => gitAsync(["checkout", "master"]));
-}
-
 function checkDocsAsync(parsed?: commandParser.ParsedCommand): Promise<void> {
     return internalCheckDocsAsync(
         true,
@@ -6156,7 +6087,6 @@ function testGithubPackagesAsync(parsed: commandParser.ParsedCommand): Promise<v
                 let tag = pxt.semver.sortLatestTags(tags)[0];
                 if (!tag) {
                     reportWarning({ repo: fullname, title: "create a release", body: "You need to create a release in this repository. Follow the instructions at https://makecode.com/extensions/versioning." });
-                    tag = "master";
                 }
                 else {
                     reportLog(`  release: ${tag}`)
@@ -6805,21 +6735,6 @@ ${pxt.crowdin.KEY_VARIABLE} - crowdin key
         }
     }, c => pyconv.convertAsync(c.args, !!c.flags["internal"]))
 
-    p.defineCommand({
-        name: "cherrypick",
-        aliases: ["cp"],
-        help: "recursively cherrypicks and push branches",
-        argString: "<commit>",
-        advanced: true,
-        flags: {
-            "name": {
-                description: "name of the branch",
-                type: "string",
-                argument: "name"
-            }
-        }
-    }, cherryPickAsync);
-
     p.defineCommand({
         name: "decompile",
         help: "decompile typescript files",
diff --git a/docs/github-explorer.html b/docs/github-explorer.html
index d7429f5610bd..005dac37d9c3 100644
--- a/docs/github-explorer.html
+++ b/docs/github-explorer.html
@@ -138,7 +138,7 @@
             login
         }
         nameWithOwner
-        object(expression: "master:pxt.json") {
+        object(expression: "HEAD:pxt.json") {
           ... on Blob {
             text
           }
@@ -251,7 +251,7 @@
 
                                 const url = targets[repo.target].url +
                                     `?nocookiebanner=1&${readOnly ? 'controller=1&readonly=1&ws=mem&' : 'editorLayout=ide&nosandbox=1'}#pub:github:`
-                                    + repo.nameWithOwner + "#master";
+                                    + repo.nameWithOwner;
                                 $("#makecodecolumn").attr("src", url);
                             });
 
diff --git a/localtypings/pxtarget.d.ts b/localtypings/pxtarget.d.ts
index 456e7a9d9693..c6177501cbdc 100644
--- a/localtypings/pxtarget.d.ts
+++ b/localtypings/pxtarget.d.ts
@@ -77,7 +77,7 @@ declare namespace pxt {
         compileService?: TargetCompileService;
         ignoreDocsErrors?: boolean;
         uploadApiStringsBranchRx?: string; // regular expression to match branches that should upload api strings
-        uploadDocs?: boolean; // enable uploading to crowdin on master or v* builds
+        uploadDocs?: boolean; // enable uploading to crowdin on default branch or v* builds
         variants?: Map<AppTarget>; // patches on top of the current AppTarget for different chip variants
         multiVariants?: string[];
         alwaysMultiVariant?: boolean;
@@ -244,7 +244,7 @@ declare namespace pxt {
         codalTarget?: string | {
             name: string; // "codal-arduino-uno"
             url: string; // "https://github.com/lancaster-university/codal-arduino-uno"
-            branch: string; // "master"
+            branch: string; // "main"
             type: string; // "git"
             branches?: pxt.Map<string>; // overrides repo url -> commit sha
         };
diff --git a/pxtlib/browserutils.ts b/pxtlib/browserutils.ts
index 3afbbdc1aea0..b617f18ef4c5 100644
--- a/pxtlib/browserutils.ts
+++ b/pxtlib/browserutils.ts
@@ -755,7 +755,7 @@ namespace pxt.BrowserUtils {
     class MemTranslationDb implements ITranslationDb {
         translations: pxt.Map<ITranslationDbEntry> = {};
         key(lang: string, filename: string, branch: string) {
-            return `${lang}|${filename}|${branch || "master"}`;
+            return `${lang}|${filename}|${branch || "default"}`;
         }
         get(lang: string, filename: string, branch: string): ITranslationDbEntry {
             return this.translations[this.key(lang, filename, branch)];
@@ -1030,6 +1030,7 @@ namespace pxt.BrowserUtils {
     }
 
     function getTutorialInfoKey(filename: string, branch?: string) {
+        // TODO: 'main' support
         return `${filename}|${branch || "master"}`;
     }
 
diff --git a/pxtlib/cpp.ts b/pxtlib/cpp.ts
index 6e856312d6a5..49b84408ff69 100644
--- a/pxtlib/cpp.ts
+++ b/pxtlib/cpp.ts
@@ -1016,7 +1016,7 @@ namespace pxt.cpp {
                 "libraries": U.values(codalLibraries).map(r => ({
                     "name": r.project,
                     "url": "https://github.com/" + r.fullName,
-                    "branch": r.tag || "master",
+                    "branch": r.tag || "master", // leave as master
                     "type": "git"
                 }))
             }
diff --git a/pxtlib/docsrender.ts b/pxtlib/docsrender.ts
index 0a1d18725b4d..99b4b3ce52ce 100644
--- a/pxtlib/docsrender.ts
+++ b/pxtlib/docsrender.ts
@@ -535,7 +535,7 @@ namespace pxt.docs {
         if (opts.repo)
             markdown += `
 \`\`\`package
-${opts.repo.name.replace(/^pxt-/, '')}=github:${opts.repo.fullName}#${opts.repo.tag || "master"}
+${opts.repo.name.replace(/^pxt-/, '')}=github:${opts.repo.fullName}${opts.repo.tag ? `#${opts.repo.tag}` : ""}
 \`\`\`
 `;
 
diff --git a/pxtlib/github.ts b/pxtlib/github.ts
index b9f769325879..083460e5e88e 100644
--- a/pxtlib/github.ts
+++ b/pxtlib/github.ts
@@ -166,19 +166,25 @@ namespace pxt.github {
         private configs: pxt.Map<pxt.PackageConfig> = {};
         private packages: pxt.Map<CachedPackage> = {};
 
-        private proxyWithCdnLoadPackageAsync(repopath: string, tag: string): Promise<CachedPackage> {
+        private async proxyWithCdnLoadPackageAsync(repopath: string, tag: string): Promise<CachedPackage> {
             // cache lookup
-            const key = `${repopath}/${tag}`;
+            const key = `${repopath}/${tag || "default"}`;
             let res = this.packages[key];
             if (res) {
-                pxt.debug(`github cache ${repopath}/${tag}/text`);
+                pxt.debug(`github cache ${repopath}/${tag || "default"}/text`);
                 return Promise.resolve(res);
             }
 
             // load and cache
             const parsed = parseRepoId(repopath)
-            return ghProxyWithCdnJsonAsync(join(parsed.slug, tag, parsed.fileName, "text"))
-                .then(v => this.packages[key] = { files: v });
+            if (!tag || tag === "default") {
+                // resolve master vs main
+                const repo: { defaultBranch: string } = await ghProxyWithCdnJsonAsync(parsed.slug)
+                tag = repo.defaultBranch
+            }
+            const v = await ghProxyWithCdnJsonAsync(join(parsed.slug, tag, parsed.fileName, "text"))
+            const r = this.packages[key] = { files: v }
+            return r;
         }
 
         private cacheConfig(key: string, v: string) {
@@ -188,8 +194,7 @@ namespace pxt.github {
         }
 
         async loadConfigAsync(repopath: string, tag: string): Promise<pxt.PackageConfig> {
-            if (!tag) tag = "master";
-
+            U.assert(!!tag)
             // cache lookup
             const key = `${repopath}/${tag}`;
             let res = this.configs[key];
@@ -214,7 +219,7 @@ namespace pxt.github {
         }
 
         async loadPackageAsync(repopath: string, tag: string): Promise<CachedPackage> {
-            if (!tag) tag = "master";
+            U.assert(!!tag)
 
             // try using github proxy first
             if (hasProxy()) {
@@ -384,7 +389,7 @@ namespace pxt.github {
         return (resp.statusCode == 200)
     }
 
-    export async function putFileAsync(repopath: string, path: string, content: string) {
+    export async function putFileAsync(repopath: string, branch: string, path: string, content: string) {
         const parsed = parseRepoId(repopath);
         await ghRequestAsync({
             url: `https://api.github.com/repos/${pxt.github.join(parsed.slug, "contents", parsed.fileName, path)}`,
@@ -393,7 +398,7 @@ namespace pxt.github {
             data: {
                 message: lf("Initialize empty repo"),
                 content: btoa(U.toUTF8(content)),
-                branch: "master"
+                branch
             },
             successCodes: [201]
         })
@@ -451,7 +456,7 @@ namespace pxt.github {
     }
 
     export function getRefAsync(repopath: string, branch: string) {
-        branch = branch || "master";
+        U.assert(!!branch)
         return ghGetJsonAsync("https://api.github.com/repos/" + repopath + "/git/refs/heads/" + branch)
             .then(resolveRefAsync)
             .catch(err => {
@@ -563,7 +568,8 @@ namespace pxt.github {
                     .then(resolveRefAsync))
     }
 
-    export function pkgConfigAsync(repopath: string, tag = "master") {
+    export function pkgConfigAsync(repopath: string, tag: string) {
+        U.assert(!!tag)
         return db.loadConfigAsync(repopath, tag)
     }
 
@@ -662,7 +668,7 @@ namespace pxt.github {
         forks: number;
         open_issues: number;
         watchers: number;
-        default_branch: string; // "master",
+        default_branch: string;
         score: number; // 6.7371006
 
         // non-github, added to track search request
@@ -701,6 +707,16 @@ namespace pxt.github {
         fork?: boolean;
     }
 
+    export function isDefaultBranch(branch: string, repo?: GitRepo) {
+        if (repo && repo.defaultBranch)
+            return branch === repo.defaultBranch;
+        return /^(main|master)$/.test(branch);
+    }
+
+    export function isDefaultOrReleaseBranch(branch: string, repo?: GitRepo) {
+        return isDefaultBranch(branch) || /^v\d+\.\d+\.\d+$/.test(branch);
+    }
+
     export function listUserReposAsync(): Promise<GitRepo[]> {
         const q = `{
   viewer {
@@ -765,7 +781,7 @@ namespace pxt.github {
         }).then(v => mkRepo(v))
     }
 
-    export async function enablePagesAsync(repo: string) {
+    export async function enablePagesAsync(repo: string, branch: string) {
         // https://developer.github.com/v3/repos/pages/#enable-a-pages-site
         // try read status
         const parsed = parseRepoId(repo);
@@ -782,7 +798,7 @@ namespace pxt.github {
             try {
                 const r = await ghPostAsync(`https://api.github.com/repos/${parsed.slug}/pages`, {
                     source: {
-                        branch: "master",
+                        branch,
                         path: "/"
                     }
                 }, {
@@ -911,7 +927,12 @@ namespace pxt.github {
         }
         // try github apis
         const r = await ghGetJsonAsync("https://api.github.com/repos/" + rid.slug)
-        return mkRepo(r, { config, fullName: rid.fullName, fileName: rid.fileName, tag: rid.tag });
+        return mkRepo(r, {
+            config,
+            fullName: rid.fullName,
+            fileName: rid.fileName,
+            tag: rid.tag,
+        });
     }
 
     function proxyRepoAsync(rid: ParsedRepo, status: GitRepoStatus): Promise<GitRepo> {
@@ -927,7 +948,7 @@ namespace pxt.github {
                     slug: rid.slug,
                     name: rid.fileName ? `${meta.name}-${rid.fileName}` : meta.name,
                     description: meta.description,
-                    defaultBranch: meta.defaultBranch || "master",
+                    defaultBranch: meta.defaultBranch,
                     tag: rid.tag,
                     status
                 };
@@ -1012,13 +1033,14 @@ namespace pxt.github {
     }
 
     export function stringifyRepo(p: ParsedRepo) {
-        return p ? "github:" + p.fullName.toLowerCase() + "#" + (p.tag || "master") : undefined;
+        return p ? "github:" + p.fullName.toLowerCase() + "#" + (p.tag || "default") : undefined;
     }
 
     export function normalizeRepoId(id: string) {
         const gid = parseRepoId(id);
         if (!gid) return undefined;
-        gid.tag = gid.tag || "master";
+        // this does not work anymore
+        gid.tag = gid.tag;
         return stringifyRepo(gid);
     }
 
diff --git a/webapp/src/data.ts b/webapp/src/data.ts
index 1b06db8afac6..c04efddc2327 100644
--- a/webapp/src/data.ts
+++ b/webapp/src/data.ts
@@ -64,12 +64,14 @@ mountVirtualApi("gh-search", {
     isOffline: () => !Cloud.isOnline(),
 })
 
+/* does not seem to be used
 mountVirtualApi("gh-pkgcfg", {
     getAsync: query =>
-        pxt.github.pkgConfigAsync(stripProtocol(query)).catch(core.handleNetworkError),
+        pxt.github.pkgConfigAsync(stripProtocol(query), ).catch(core.handleNetworkError),
     expirationTime: p => 60 * 1000,
     isOffline: () => !Cloud.isOnline(),
 })
+*/
 
 // gh-commits:repo#sha
 mountVirtualApi("gh-commits", {
@@ -95,7 +97,8 @@ mountVirtualApi("target-config", {
                         pxt.storage.setLocal("targetconfig", JSON.stringify(js))
                         invalidate("target-config");
                         invalidate("gh-search");
-                        invalidate("gh-pkgcfg");
+                        // does not seem to be used
+                        // invalidate("gh-pkgcfg");
                     }
                     return js;
                 })
diff --git a/webapp/src/db.ts b/webapp/src/db.ts
index 120c793d5809..cb73ad948666 100644
--- a/webapp/src/db.ts
+++ b/webapp/src/db.ts
@@ -96,8 +96,9 @@ class GithubDb implements pxt.github.IGithubDb {
     private table = new Table("github");
 
     loadConfigAsync(repopath: string, tag: string): Promise<pxt.PackageConfig> {
+        pxt.U.assert(!!tag)
         // don't cache master
-        if (tag == "master")
+        if (pxt.github.isDefaultBranch(tag))
             return this.mem.loadConfigAsync(repopath, tag);
 
         const id = `config-${repopath}-${tag}`;
@@ -119,9 +120,9 @@ class GithubDb implements pxt.github.IGithubDb {
         );
     }
     loadPackageAsync(repopath: string, tag: string): Promise<pxt.github.CachedPackage> {
-        tag = tag || "master";
+        pxt.U.assert(!!tag)
         // don't cache master
-        if (tag == "master")
+        if (pxt.github.isDefaultBranch(tag))
             return this.mem.loadPackageAsync(repopath, tag);
 
         const id = `pkg-${repopath}-${tag}`;
diff --git a/webapp/src/dialogs.tsx b/webapp/src/dialogs.tsx
index e236420a9de7..77dc6f6e6517 100644
--- a/webapp/src/dialogs.tsx
+++ b/webapp/src/dialogs.tsx
@@ -81,7 +81,7 @@ function renderCompileLink(variantName: string, cs: pxt.TargetCompileService) {
 
     if (typeof cs.codalTarget === "object" && typeof cs.codalTarget.url === "string") {
         url = cs.codalTarget.branch ? pxt.BrowserUtils.joinURLs(cs.codalTarget.url, "releases/tag", cs.codalTarget.branch) : cs.codalTarget.url;
-        version = cs.codalTarget.branch || "master";
+        version = cs.codalTarget.branch || "master"; // leave as "master"
         name = cs.codalTarget.name || cs.serviceId;
     }
     else {
diff --git a/webapp/src/githubbutton.tsx b/webapp/src/githubbutton.tsx
index a01faf9b878c..7a9d6f147202 100644
--- a/webapp/src/githubbutton.tsx
+++ b/webapp/src/githubbutton.tsx
@@ -63,10 +63,10 @@ export class GithubButton extends sui.UIElement<GithubButtonProps, GithubButtonS
         const hasissue = pullStatus == workspace.PullStatus.BranchNotFound;
         const haspull = pullStatus == workspace.PullStatus.GotChanges;
         const modified = meta && !!meta.modified;
-        const repoName = ghid.project && ghid.tag ? `${ghid.project}${ghid.tag == "master" ? "" : `#${ghid.tag}`}` : ghid.fullName;
+        const repoName = ghid.project && ghid.tag ? `${ghid.project}${pxt.github.isDefaultBranch(ghid.tag) ? "" : `#${ghid.tag}`}` : ghid.fullName;
         // shrink name...
         const maxLength = 20;
-        let displayName = ghid.tag && ghid.tag != "master" ? `#${ghid.tag}` : "";
+        let displayName = ghid.tag && !pxt.github.isDefaultBranch(ghid.tag) ? `#${ghid.tag}` : "";
         if (displayName.length > maxLength)
             displayName = displayName.slice(0, maxLength - 2) + '..';
 
@@ -84,11 +84,10 @@ export class GithubButton extends sui.UIElement<GithubButtonProps, GithubButtonS
         >
             <i className="github icon" />
             <span className="ui mobile hide">{displayName}</span>
-            <i className={`ui long ${
-                hasissue ? "exclamation circle"
-                    : haspull ? "arrow alternate down"
-                        : modified ? "arrow alternate up"
-                            : "check"} icon mobile hide`} />
+            <i className={`ui long ${hasissue ? "exclamation circle"
+                : haspull ? "arrow alternate down"
+                    : modified ? "arrow alternate up"
+                        : "check"} icon mobile hide`} />
         </div>;
     }
 }
diff --git a/webapp/src/gitjson.tsx b/webapp/src/gitjson.tsx
index 3ba367bc1f7d..68daf0af9f14 100644
--- a/webapp/src/gitjson.tsx
+++ b/webapp/src/gitjson.tsx
@@ -165,10 +165,17 @@ class GithubComponent extends data.Component<GithubProps, GithubState> {
         await f.setContentAsync(JSON.stringify(gs, null, 4))
     }
 
-    private async switchProjectToBranchAsync(newBranch: string) {
+    private async switchProjectToBranchAsync(newBranch?: string) {
         const { header } = this.props.parent.state;
         const gs = this.getGitJson();
         const parsed = this.parsedRepoId()
+
+        if (!newBranch) {
+            const packagesConfig = await pxt.packagesConfigAsync()
+            const repo = await pxt.github.repoAsync(parsed.slug, packagesConfig)
+            newBranch = repo.defaultBranch
+        }
+
         header.githubId = parsed.fullName + "#" + newBranch
         gs.repo = header.githubId
         await this.saveGitJsonAsync(gs)
@@ -208,7 +215,7 @@ class GithubComponent extends data.Component<GithubProps, GithubState> {
         }
     }
 
-    public async switchBranchAsync(branch: string) {
+    public async switchBranchAsync(branch?: string) {
         await this.setStateAsync({ needsCommitMessage: false });
         const prevBranch = this.parsedRepoId().tag
         try {
@@ -234,7 +241,7 @@ class GithubComponent extends data.Component<GithubProps, GithubState> {
         }))
 
         // only branch from master...
-        if (gid.tag == "master") {
+        if (pxt.github.isDefaultBranch(gid.tag)) {
             branchList.unshift({
                 name: lf("Create new branch"),
                 description: lf("Based on {0}", gid.tag),
@@ -693,7 +700,9 @@ class GithubComponent extends data.Component<GithubProps, GithubState> {
 
             `
             */
-            const id = await pxt.github.createPRFromBranchAsync(gh.slug, "master", gh.tag, title, msg);
+            const packagesConfig = await pxt.packagesConfigAsync()
+            const repo = await pxt.github.repoAsync(gh.slug, packagesConfig)
+            const id = await pxt.github.createPRFromBranchAsync(gh.slug, repo.defaultBranch, gh.tag, title, msg);
             data.invalidateHeader("pkg-git-pr", this.props.parent.state.header);
             core.infoNotification(lf("Pull request created successfully!", id));
         } catch (e) {
@@ -749,15 +758,15 @@ class GithubComponent extends data.Component<GithubProps, GithubState> {
         const hasissue = pullStatus == workspace.PullStatus.BranchNotFound || pullStatus == workspace.PullStatus.NoSourceControl;
         const haspull = pullStatus == workspace.PullStatus.GotChanges;
         const githubId = this.parsedRepoId()
-        const master = githubId.tag == "master";
+        const isDefaultBranch = pxt.github.isDefaultBranch(githubId.tag);
         const user = this.getData("github:user") as pxt.editor.UserInfo;
 
         // don't use gs.prUrl, as it gets cleared often
-        const url = `https://github.com/${githubId.slug}/${master && !githubId.fileName ? "" : pxt.github.join("tree", githubId.tag || "master", githubId.fileName)}`;
+        const url = `https://github.com/${githubId.slug}}`;
         const needsToken = !pxt.github.token;
         // this will show existing PR if any
         const pr: pxt.github.PullRequest = this.getData("pkg-git-pr:" + header.id)
-        const showPr = pr !== null && (gs.isFork || !master);
+        const showPr = pr !== null && (gs.isFork || !isDefaultBranch);
         const showPrResolved = showPr && pr && pr.number > 0;
         const showPrCreate = showPr && pr && pr.number <= 0;
         const isOwner = user && user.id === githubId.owner;
@@ -778,7 +787,7 @@ class GithubComponent extends data.Component<GithubProps, GithubState> {
                         <sui.Link className="ui button" icon="external alternate" href={url} title={lf("Open repository in GitHub.")} target="_blank" onKeyDown={sui.fireClickOnEnter} />
                     </div>
                 </div>
-                <MessageComponent parent={this} needsToken={needsToken} githubId={githubId} master={master} gs={gs} isBlocks={isBlocksMode} needsCommit={needsCommit} user={user} pullStatus={pullStatus} pullRequest={pr} />
+                <MessageComponent parent={this} needsToken={needsToken} githubId={githubId} isDefaultBranch={isDefaultBranch} gs={gs} isBlocks={isBlocksMode} needsCommit={needsCommit} user={user} pullStatus={pullStatus} pullRequest={pr} />
                 <div className="ui form">
                     {showPrResolved &&
                         <sui.Link href={pr.url} role="button" className="ui tiny basic button create-pr"
@@ -791,12 +800,12 @@ class GithubComponent extends data.Component<GithubProps, GithubState> {
                         <span className="repo-name">{githubId.fullName}</span>
                         <span onClick={this.handleBranchClick} onKeyDown={sui.fireClickOnEnter} tabIndex={0} role="button" className="repo-branch">{"#" + githubId.tag}<i className="dropdown icon" /></span>
                     </h3>
-                    {needsCommit && <CommmitComponent parent={this} needsToken={needsToken} githubId={githubId} master={master} gs={gs} isBlocks={isBlocksMode} needsCommit={needsCommit} user={user} pullStatus={pullStatus} pullRequest={pr} />}
-                    {showPrResolved && !needsCommit && <PullRequestZone parent={this} needsToken={needsToken} githubId={githubId} master={master} gs={gs} isBlocks={isBlocksMode} needsCommit={needsCommit} user={user} pullStatus={pullStatus} pullRequest={pr} />}
+                    {needsCommit && <CommmitComponent parent={this} needsToken={needsToken} githubId={githubId} isDefaultBranch={isDefaultBranch} gs={gs} isBlocks={isBlocksMode} needsCommit={needsCommit} user={user} pullStatus={pullStatus} pullRequest={pr} />}
+                    {showPrResolved && !needsCommit && <PullRequestZone parent={this} needsToken={needsToken} githubId={githubId} isDefaultBranch={isDefaultBranch} gs={gs} isBlocks={isBlocksMode} needsCommit={needsCommit} user={user} pullStatus={pullStatus} pullRequest={pr} />}
                     {diffFiles && <DiffView parent={this} diffFiles={diffFiles} cacheKey={gs.commit.sha} allowRevert={true} showWhitespaceDiff={true} blocksMode={isBlocksMode} showConflicts={true} />}
-                    <HistoryZone parent={this} needsToken={needsToken} githubId={githubId} master={master} gs={gs} isBlocks={isBlocksMode} needsCommit={needsCommit} user={user} pullStatus={pullStatus} pullRequest={pr} />
-                    {master && <ReleaseZone parent={this} needsToken={needsToken} githubId={githubId} master={master} gs={gs} isBlocks={isBlocksMode} needsCommit={needsCommit} user={user} pullStatus={pullStatus} pullRequest={pr} />}
-                    {!isBlocksMode && <ExtensionZone parent={this} needsToken={needsToken} githubId={githubId} master={master} gs={gs} isBlocks={isBlocksMode} needsCommit={needsCommit} user={user} pullStatus={pullStatus} pullRequest={pr} />}
+                    <HistoryZone parent={this} needsToken={needsToken} githubId={githubId} isDefaultBranch={isDefaultBranch} gs={gs} isBlocks={isBlocksMode} needsCommit={needsCommit} user={user} pullStatus={pullStatus} pullRequest={pr} />
+                    {isDefaultBranch && <ReleaseZone parent={this} needsToken={needsToken} githubId={githubId} isDefaultBranch={isDefaultBranch} gs={gs} isBlocks={isBlocksMode} needsCommit={needsCommit} user={user} pullStatus={pullStatus} pullRequest={pr} />}
+                    {!isBlocksMode && <ExtensionZone parent={this} needsToken={needsToken} githubId={githubId} isDefaultBranch={isDefaultBranch} gs={gs} isBlocks={isBlocksMode} needsCommit={needsCommit} user={user} pullStatus={pullStatus} pullRequest={pr} />}
                     <div></div>
                 </div>
             </div>
@@ -1142,8 +1151,8 @@ ${content}
             </div>
             {displayDiffFiles.map(df => this.showDiff(df))}
         </div> : <div className={`ui ${invertedTheme ? "inverted " : ""}segment`}>
-                {lf("No local changes found.")}
-            </div>;
+            {lf("No local changes found.")}
+        </div>;
     }
 }
 
@@ -1153,10 +1162,10 @@ class MessageComponent extends sui.StatelessUIElement<GitHubViewProps> {
         this.handleSwitchMasterBranch = this.handleSwitchMasterBranch.bind(this);
     }
 
-    private handleSwitchMasterBranch(e: React.MouseEvent<HTMLElement>) {
+    private async handleSwitchMasterBranch(e: React.MouseEvent<HTMLElement>) {
         pxt.tickEvent("github.branch.switch");
         e.stopPropagation();
-        this.props.parent.switchBranchAsync("master");
+        this.props.parent.switchBranchAsync();
     }
 
     renderCore() {
@@ -1207,7 +1216,7 @@ class MessageComponent extends sui.StatelessUIElement<GitHubViewProps> {
 interface GitHubViewProps {
     githubId: pxt.github.ParsedRepo;
     needsToken: boolean;
-    master: boolean;
+    isDefaultBranch: boolean;
     parent: GithubComponent;
     gs: pxt.github.GitJson;
     isBlocks: boolean;
@@ -1357,7 +1366,7 @@ class ReleaseZone extends sui.StatelessUIElement<GitHubViewProps> {
     private handleBumpClick(e: React.MouseEvent<HTMLElement>) {
         pxt.tickEvent("github.releasezone.bump", undefined, { interactiveConsent: true });
         e.stopPropagation();
-        const { needsCommit, master } = this.props;
+        const { needsCommit, isDefaultBranch } = this.props;
         const header = this.props.parent.props.parent.state.header;
         if (needsCommit)
             core.confirmAsync({
@@ -1366,10 +1375,10 @@ class ReleaseZone extends sui.StatelessUIElement<GitHubViewProps> {
                 agreeLbl: lf("Ok"),
                 hideAgree: true
             });
-        else if (!master)
+        else if (!isDefaultBranch)
             core.confirmAsync({
-                header: lf("Checkout the master branch..."),
-                body: lf("You need to checkout the master branch to create a release."),
+                header: lf("Checkout the default branch..."),
+                body: lf("You need to checkout the default branch to create a release."),
                 agreeLbl: lf("Ok"),
                 hideAgree: true
             });
diff --git a/webapp/src/package.ts b/webapp/src/package.ts
index af90483418a0..049a600a167d 100644
--- a/webapp/src/package.ts
+++ b/webapp/src/package.ts
@@ -936,7 +936,7 @@ data.mountVirtualApi("pkg-git-pr", {
         const ghid = f.getPkgId() == "this" && header && header.githubId;
         if (!ghid) return Promise.resolve(missing);
         const parsed = pxt.github.parseRepoId(ghid);
-        if (!parsed || !parsed.tag || parsed.tag == "master") return Promise.resolve(missing);
+        if (!parsed || !parsed.tag || pxt.github.isDefaultBranch(parsed.tag)) return Promise.resolve(missing);
         return pxt.github.findPRNumberforBranchAsync(parsed.fullName, parsed.tag)
             .catch(e => missing);
     },
diff --git a/webapp/src/workspace.ts b/webapp/src/workspace.ts
index 57050a427e99..d35b13e4e341 100644
--- a/webapp/src/workspace.ts
+++ b/webapp/src/workspace.ts
@@ -370,7 +370,7 @@ interface ProjectChanges {
     header: Change<keyof Header, string>[],
     files: Change<string, number>[],
 }
-function computeChangeSummary(a: {header: Header, text: ScriptText}, b: {header: Header, text: ScriptText}): ProjectChanges {
+function computeChangeSummary(a: { header: Header, text: ScriptText }, b: { header: Header, text: ScriptText }): ProjectChanges {
     const aHdr = a.header || {} as Header
     const bHdr = b.header || {} as Header
     const aTxt = a.text || {}
@@ -383,22 +383,22 @@ function computeChangeSummary(a: {header: Header, text: ScriptText}, b: {header:
     const hasHdrChanged = (k: HeaderK) => hasObjChanged(aHdr[k], bHdr[k])
     const hdrChanges = hdrKeys.filter(hasHdrChanged)
     const hdrDels = hdrChanges.filter(k => (k in aHdr) && !(k in bHdr))
-        .map(k => ({kind: 'del', key: k, oldVal: aHdr[k]}) as Change<HeaderK, string>)
+        .map(k => ({ kind: 'del', key: k, oldVal: aHdr[k] }) as Change<HeaderK, string>)
     const hdrAdds = hdrChanges.filter(k => !(k in aHdr) && (k in bHdr))
-        .map(k => ({kind: 'add', key: k, newVal: bHdr[k]}) as Change<HeaderK, string>)
+        .map(k => ({ kind: 'add', key: k, newVal: bHdr[k] }) as Change<HeaderK, string>)
     const hdrMods = hdrChanges.filter(k => (k in aHdr) && (k in bHdr))
-        .map(k => ({kind: 'mod', key: k, oldVal: aHdr[k], newVal: bHdr[k]}) as Change<HeaderK, string>)
+        .map(k => ({ kind: 'mod', key: k, oldVal: aHdr[k], newVal: bHdr[k] }) as Change<HeaderK, string>)
 
     // files
     const filenames = U.unique([...Object.keys(aTxt), ...Object.keys(bTxt)], s => s)
     const hasFileChanged = (filename: string) => aTxt[filename] !== bTxt[filename]
     const fileChanges = filenames.filter(hasFileChanged)
     const fileDels = fileChanges.filter(k => (k in aTxt) && !(k in bTxt) && !!b.text)
-        .map(k => ({kind: 'del', key: k, oldVal: aTxt[k].length}) as Change<string, number>)
+        .map(k => ({ kind: 'del', key: k, oldVal: aTxt[k].length }) as Change<string, number>)
     const fileAdds = fileChanges.filter(k => !(k in aTxt) && (k in bTxt))
-        .map(k => ({kind: 'add', key: k, newVal: bTxt[k].length}) as Change<string, number>)
+        .map(k => ({ kind: 'add', key: k, newVal: bTxt[k].length }) as Change<string, number>)
     const fileMods = fileChanges.filter(k => (k in aTxt) && (k in bTxt))
-        .map(k => ({kind: 'mod', key: k, oldVal: aTxt[k].length, newVal: bTxt[k].length}) as Change<string, number>)
+        .map(k => ({ kind: 'mod', key: k, oldVal: aTxt[k].length, newVal: bTxt[k].length }) as Change<string, number>)
 
     return {
         header: [...hdrDels, ...hdrAdds, ...hdrMods],
@@ -408,7 +408,7 @@ function computeChangeSummary(a: {header: Header, text: ScriptText}, b: {header:
 // useful for debugging
 function stringifyChangeSummary(diff: ProjectChanges): string {
     const indent = (s: string) => '\t' + s
-    const changeToStr = (c: Change<any,any>) => `${c.kind} ${c.key}: (${c.oldVal || ''}) => (${c.newVal || ''})`
+    const changeToStr = (c: Change<any, any>) => `${c.kind} ${c.key}: (${c.oldVal || ''}) => (${c.newVal || ''})`
     let res = ''
 
     const hdrDels = diff.header.filter(k => k.kind === 'del')
@@ -442,7 +442,7 @@ export async function partialSaveAsync(id: string, filename: string, content: st
         pxt.tickEvent(`workspace.invalidSaveToUnknownProject`);
         return;
     }
-    const newTxt = {...await getTextAsync(id)}
+    const newTxt = { ...await getTextAsync(id) }
     newTxt[filename] = content;
     return saveAsync(prev.header, newTxt);
 }
@@ -479,7 +479,7 @@ export async function saveAsync(h: Header, text?: ScriptText, fromCloudSync?: bo
             return true
         }
         const prevProj = e
-        const allChanges = computeChangeSummary(prevProj, {header: h, text})
+        const allChanges = computeChangeSummary(prevProj, { header: h, text })
         const ignoredFiles = [GIT_JSON, pxt.SIMSTATE_JSON, pxt.SERIAL_EDITOR_FILE]
         const ignoredHeaderFields: (keyof Header)[] = ['recentUse', 'modificationTime', 'cloudCurrent', '_rev', '_id' as keyof Header, 'cloudVersion']
         const userChanges: ProjectChanges = {
@@ -801,10 +801,10 @@ export async function hasMergeConflictMarkersAsync(hd: Header): Promise<boolean>
 export async function prAsync(hd: Header, commitId: string, msg: string) {
     let parsed = pxt.github.parseRepoId(hd.githubId)
     // merge conflict - create a Pull Request
-    const branchName = await pxt.github.getNewBranchNameAsync(parsed.slug, "merge-")
-    await pxt.github.createNewBranchAsync(parsed.slug, branchName, commitId)
-    const url = await pxt.github.createPRFromBranchAsync(parsed.slug, parsed.tag, branchName, msg)
-    // force user back to master - we will instruct them to merge PR in github.com website
+    const branchName = await pxt.github.getNewBranchNameAsync(parsed.fullName, "merge-")
+    await pxt.github.createNewBranchAsync(parsed.fullName, branchName, commitId)
+    const url = await pxt.github.createPRFromBranchAsync(parsed.fullName, parsed.tag, branchName, msg)
+    // force user back to default branch - we will instruct them to merge PR in github.com website
     // and sync here to get the changes
     let headCommit = await pxt.github.getRefAsync(parsed.slug, parsed.tag)
     await githubUpdateToAsync(hd, {
@@ -911,7 +911,7 @@ export async function commitAsync(hd: Header, options: CommitOptions = {}) {
     // add compiled javascript to be run in github pages
     if (pxt.appTarget.appTheme.githubCompiledJs
         && options.binaryJs
-        && (!parsed.tag || parsed.tag == "master")) {
+        && (!parsed.tag || pxt.github.isDefaultBranch(parsed.tag))) {
         const v = cfg.version || "0.0.0";
         const opts: compiler.CompileOptions = {
             jsMetaVersion: v
@@ -966,10 +966,10 @@ export async function commitAsync(hd: Header, options: CommitOptions = {}) {
             files,
             saveTag: options.createRelease
         })
-        if (options.createRelease) {
+        if (options.createRelease && pxt.github.isDefaultBranch(parsed.tag)) {
             await pxt.github.createReleaseAsync(parsed.slug, options.createRelease, newCommit)
             // ensure pages are on
-            await pxt.github.enablePagesAsync(parsed.slug);
+            await pxt.github.enablePagesAsync(parsed.slug, parsed.tag);
             // clear the cloud cache
             await pxt.github.listRefsAsync(parsed.slug, "tags", true, true);
         }
@@ -1218,7 +1218,12 @@ async function githubUpdateToAsync(hd: Header, options: UpdateOptions) {
 export async function exportToGithubAsync(hd: Header, repoid: string) {
     const parsed = pxt.github.parseRepoId(repoid);
     const pfiles = pxt.template.packageFiles(hd.name);
-    await pxt.github.putFileAsync(parsed.fullName, ".gitignore", pfiles[".gitignore"]);
+    if (!parsed.tag) {
+        const packagesConfig = await pxt.packagesConfigAsync()
+        const repo = await pxt.github.repoAsync(parsed.slug, packagesConfig)
+        parsed.tag = repo.defaultBranch
+    }
+    await pxt.github.putFileAsync(parsed.fullName, parsed.tag, ".gitignore", pfiles[".gitignore"]);
     const sha = await pxt.github.getRefAsync(parsed.slug, parsed.tag)
     const commit = await pxt.github.getCommitAsync(parsed.slug, sha)
     const files = await getTextAsync(hd.id)
@@ -1434,7 +1439,7 @@ export async function initializeGithubRepoAsync(hd: Header, repoid: string, forc
 
     // try enable github pages
     try {
-        await pxt.github.enablePagesAsync(parsed.slug);
+        await pxt.github.enablePagesAsync(parsed.slug, parsed.tag);
     } catch (e) {
         pxt.reportException(e);
     }
@@ -1450,7 +1455,14 @@ export async function importGithubAsync(id: string): Promise<Header> {
     let isEmpty = false
     let forceTemplateFiles = false;
     try {
+        const packagesConfig = await pxt.packagesConfigAsync()
+        const repo = await pxt.github.repoAsync(parsed.slug, packagesConfig)
+        if (!repo)
+            U.userError(`unable to find repository`)
+        parsed.tag = repo.defaultBranch
         sha = await pxt.github.getRefAsync(parsed.slug, parsed.tag)
+        if (!sha)
+            U.userError(`unable to find branch`)
         // if the repo does not have a pxt.json file, treat as empty
         // (must be done before)
         const commit = await pxt.github.getCommitAsync(parsed.slug, sha)
@@ -1480,7 +1492,7 @@ export async function importGithubAsync(id: string): Promise<Header> {
             if (pxt.shell.isReadOnly())
                 U.userError(lf("This repository looks empty."));
             await cloudsync.ensureGitHubTokenAsync();
-            await pxt.github.putFileAsync(parsed.fullName, ".gitignore", "# Initial\n");
+            await pxt.github.putFileAsync(parsed.fullName, parsed.tag, ".gitignore", "# Initial\n");
             isEmpty = true;
             forceTemplateFiles = true;
             sha = await pxt.github.getRefAsync(parsed.slug, parsed.tag)
@@ -1620,7 +1632,7 @@ export function fireEvent(ev: pxt.editor.events.Event) {
 }
 
 // debug helpers
-const _abrvStrs: {[key: string]: string} = {};
+const _abrvStrs: { [key: string]: string } = {};
 let _abrvNextInt = 1;
 function dbgShorten(s: string): string {
     if (!s)