diff --git a/__test__/projects/GitHubProjectDataSource.test.ts b/__test__/projects/GitHubProjectDataSource.test.ts
index 874caf3d..14d0df5b 100644
--- a/__test__/projects/GitHubProjectDataSource.test.ts
+++ b/__test__/projects/GitHubProjectDataSource.test.ts
@@ -1091,3 +1091,252 @@ test("It identifies the default branch in returned versions", async () => {
     .map(e => e.name)
   expect(defaultVersionNames).toEqual(["development"])
 })
+
+test("It adds remote versions from the project configuration", async () => {
+  const rawProjectConfig = `
+  remoteVersions:
+    - name: Anne
+      specifications:
+      - name: Huey
+        url: https://example.com/huey.yml
+      - name: Dewey
+        url: https://example.com/dewey.yml
+    - name: Bobby
+      specifications:
+      - name: Louie
+        url: https://example.com/louie.yml
+  `
+  const sut = new GitHubProjectDataSource({
+    dataSource: {
+      async getRepositories() {
+        return [{
+          name: "foo",
+          owner: {
+            login: "acme"
+          },
+          defaultBranchRef: {
+            name: "main",
+            target: {
+              oid: "12345678"
+            }
+          },
+          configYml: {
+            text: rawProjectConfig
+          },
+          branches: {
+            edges: []
+          },
+          tags: {
+            edges: []
+          }
+        }]
+      }
+    }
+  })
+  const projects = await sut.getProjects()
+  expect(projects[0].versions).toEqual([{
+    id: "anne",
+    name: "Anne",
+    isDefault: false,
+    specifications: [{
+      id: "huey",
+      name: "Huey",
+      url: `/api/proxy?url=${encodeURIComponent("https://example.com/huey.yml")}`
+    }, {
+      id: "dewey",
+      name: "Dewey",
+      url: `/api/proxy?url=${encodeURIComponent("https://example.com/dewey.yml")}`
+    }]
+  }, {
+    id: "bobby",
+    name: "Bobby",
+    isDefault: false,
+    specifications: [{
+      id: "louie",
+      name: "Louie",
+      url: `/api/proxy?url=${encodeURIComponent("https://example.com/louie.yml")}`
+    }]
+  }])
+})
+
+test("It modifies ID of remote version if the ID already exists", async () => {
+  const rawProjectConfig = `
+  remoteVersions:
+    - name: Bar
+      specifications:
+      - name: Baz
+        url: https://example.com/baz.yml
+    - name: Bar
+      specifications:
+      - name: Hello
+        url: https://example.com/hello.yml
+  `
+  const sut = new GitHubProjectDataSource({
+    dataSource: {
+      async getRepositories() {
+        return [{
+          name: "foo",
+          owner: {
+            login: "acme"
+          },
+          defaultBranchRef: {
+            name: "bar",
+            target: {
+              oid: "12345678"
+            }
+          },
+          configYml: {
+            text: rawProjectConfig
+          },
+          branches: {
+            edges: [{
+              node: {
+                name: "bar",
+                target: {
+                  oid: "12345678",
+                  tree: {
+                    entries: [{
+                      name: "openapi.yml"
+                    }]
+                  }
+                }
+              }
+            }]
+          },
+          tags: {
+            edges: []
+          }
+        }]
+      }
+    }
+  })
+  const projects = await sut.getProjects()
+  expect(projects[0].versions).toEqual([{
+    id: "bar",
+    name: "bar",
+    url: "https://github.com/acme/foo/tree/bar",
+    isDefault: true,
+    specifications: [{
+      id: "openapi.yml",
+      name: "openapi.yml",
+      url: "/api/blob/acme/foo/openapi.yml?ref=12345678",
+      editURL: "https://github.com/acme/foo/edit/bar/openapi.yml"
+    }]
+  }, {
+    id: "bar1",
+    name: "Bar",
+    isDefault: false,
+    specifications: [{
+      id: "baz",
+      name: "Baz",
+      url: `/api/proxy?url=${encodeURIComponent("https://example.com/baz.yml")}`
+    }]
+  }, {
+    id: "bar2",
+    name: "Bar",
+    isDefault: false,
+    specifications: [{
+      id: "hello",
+      name: "Hello",
+      url: `/api/proxy?url=${encodeURIComponent("https://example.com/hello.yml")}`
+    }]
+  }])
+})
+
+test("It lets users specify the ID of a remote version", async () => {
+  const rawProjectConfig = `
+  remoteVersions:
+    - id: some-version
+      name: Bar
+      specifications:
+      - name: Baz
+        url: https://example.com/baz.yml
+  `
+  const sut = new GitHubProjectDataSource({
+    dataSource: {
+      async getRepositories() {
+        return [{
+          name: "foo",
+          owner: {
+            login: "acme"
+          },
+          defaultBranchRef: {
+            name: "bar",
+            target: {
+              oid: "12345678"
+            }
+          },
+          configYml: {
+            text: rawProjectConfig
+          },
+          branches: {
+            edges: []
+          },
+          tags: {
+            edges: []
+          }
+        }]
+      }
+    }
+  })
+  const projects = await sut.getProjects()
+  expect(projects[0].versions).toEqual([{
+    id: "some-version",
+    name: "Bar",
+    isDefault: false,
+    specifications: [{
+      id: "baz",
+      name: "Baz",
+      url: `/api/proxy?url=${encodeURIComponent("https://example.com/baz.yml")}`
+    }]
+  }])
+})
+
+test("It lets users specify the ID of a remote specification", async () => {
+  const rawProjectConfig = `
+  remoteVersions:
+    - name: Bar
+      specifications:
+      - id: some-spec
+        name: Baz
+        url: https://example.com/baz.yml
+  `
+  const sut = new GitHubProjectDataSource({
+    dataSource: {
+      async getRepositories() {
+        return [{
+          name: "foo",
+          owner: {
+            login: "acme"
+          },
+          defaultBranchRef: {
+            name: "bar",
+            target: {
+              oid: "12345678"
+            }
+          },
+          configYml: {
+            text: rawProjectConfig
+          },
+          branches: {
+            edges: []
+          },
+          tags: {
+            edges: []
+          }
+        }]
+      }
+    }
+  })
+  const projects = await sut.getProjects()
+  expect(projects[0].versions).toEqual([{
+    id: "bar",
+    name: "Bar",
+    isDefault: false,
+    specifications: [{
+      id: "some-spec",
+      name: "Baz",
+      url: `/api/proxy?url=${encodeURIComponent("https://example.com/baz.yml")}`
+    }]
+  }])
+})
diff --git a/__test__/projects/getSelection.test.ts b/__test__/projects/getSelection.test.ts
index f2abf99f..a3979b44 100644
--- a/__test__/projects/getSelection.test.ts
+++ b/__test__/projects/getSelection.test.ts
@@ -230,3 +230,27 @@ test("It returns a undefined specification when the selected specification canno
   expect(sut.version!.id).toEqual("bar")
   expect(sut.specification).toBeUndefined()
 })
+
+test("It moves specification ID to version ID if needed", () => {
+  const sut = getSelection({
+    path: "/foo/bar/baz",
+    projects: [{
+      id: "foo",
+      name: "foo",
+      displayName: "foo",
+      versions: [{
+        id: "bar/baz",
+        name: "bar",
+        isDefault: false,
+        specifications: [{
+          id: "hello",
+          name: "hello.yml",
+          url: "https://example.com/hello.yml"
+        }]
+      }]
+    }]
+  })
+  expect(sut.project!.id).toEqual("foo")
+  expect(sut.version!.id).toEqual("bar/baz")
+  expect(sut.specification!.id).toEqual("hello")
+})
diff --git a/src/app/api/proxy/route.ts b/src/app/api/proxy/route.ts
new file mode 100644
index 00000000..7245898c
--- /dev/null
+++ b/src/app/api/proxy/route.ts
@@ -0,0 +1,17 @@
+import { NextRequest, NextResponse } from "next/server"
+import { makeAPIErrorResponse } from "@/common"
+
+export async function GET(req: NextRequest) {
+  const rawURL = req.nextUrl.searchParams.get("url")
+  if (!rawURL) {
+    return makeAPIErrorResponse(400, "Missing \"url\" query parameter.")
+  }
+  let url: URL
+  try {
+    url = new URL(rawURL)
+  } catch {
+    return makeAPIErrorResponse(400, "Invalid \"url\" query parameter.")
+  }
+  const file = await fetch(url).then(r => r.blob())
+  return new NextResponse(file, { status: 200 })
+}
diff --git a/src/features/projects/data/GitHubProjectDataSource.ts b/src/features/projects/data/GitHubProjectDataSource.ts
index bdf126c4..f94d58f6 100644
--- a/src/features/projects/data/GitHubProjectDataSource.ts
+++ b/src/features/projects/data/GitHubProjectDataSource.ts
@@ -3,10 +3,11 @@ import GitHubProjectRepository, {
 } from "./GitHubProjectRepository"
 import {
   Project,
+  Version,
   IProjectConfig,
   IProjectDataSource,
-  Version, 
-  ProjectConfigParser
+  ProjectConfigParser,
+  ProjectConfigRemoteVersion,
 } from "../domain"
 
 interface IGitHubProjectRepositoryDataSource {
@@ -48,14 +49,21 @@ export default class GitHubProjectDataSource implements IProjectDataSource {
         ref: repository.defaultBranchRef.target.oid
       })
     }
+    const versions = this.sortVersions(
+      this.addRemoteVersions(
+        this.getVersions(repository),
+        config?.remoteVersions || []
+      ),
+      repository.defaultBranchRef.name
+    ).filter(version => {
+      return version.specifications.length > 0
+    })
     const defaultName = repository.name.replace(/-openapi$/, "")
     return {
       id: defaultName,
       name: defaultName,
       displayName: config?.name || defaultName,
-      versions: this.getVersions(repository).filter(version => {
-        return version.specifications.length > 0
-      }),
+      versions,
       imageURL: imageURL
     }
   }
@@ -86,27 +94,7 @@ export default class GitHubProjectDataSource implements IProjectDataSource {
         ref: edge.node
       })
     })
-    const defaultBranchName = repository.defaultBranchRef.name
-    const candidateDefaultBranches = [
-      defaultBranchName, "main", "master", "develop", "development"
-    ]
-    // Reverse them so the top-priority branches end up at the top of the list.
-    .reverse()
-    const allVersions = branchVersions.concat(tagVersions).sort((a: Version, b: Version) => {
-      return a.name.localeCompare(b.name)
-    })
-    // Move the top-priority branches to the top of the list.
-    for (const candidateDefaultBranch of candidateDefaultBranches) {
-      const defaultBranchIndex = allVersions.findIndex((version: Version) => {
-        return version.name === candidateDefaultBranch
-      })
-      if (defaultBranchIndex !== -1) {
-        const branchVersion = allVersions[defaultBranchIndex]
-        allVersions.splice(defaultBranchIndex, 1)
-        allVersions.splice(0, 0, branchVersion)
-      }
-    }
-    return allVersions
+    return branchVersions.concat(tagVersions)
   }
   
   private mapVersionFromRef({
@@ -163,4 +151,65 @@ export default class GitHubProjectDataSource implements IProjectDataSource {
   }): string {
     return `/api/blob/${ownerName}/${repositoryName}/${path}?ref=${ref}`
   }
+  
+  private addRemoteVersions(
+    existingVersions: Version[],
+    remoteVersions: ProjectConfigRemoteVersion[]
+  ): Version[] {
+    const versions = [...existingVersions]
+    const versionIds = versions.map(e => e.id)
+    for (const remoteVersion of remoteVersions) {
+      const baseVersionId = this.makeURLSafeID(
+        (remoteVersion.id || remoteVersion.name).toLowerCase()
+      )
+      // If the version ID exists then we suffix it with a number to ensure unique versions.
+      // E.g. if "foo" already exists, we make it "foo1".
+      const existingVersionIdCount = versionIds.filter(e => e == baseVersionId).length
+      const versionId = baseVersionId + (existingVersionIdCount > 0 ? existingVersionIdCount : "")
+      const specifications = remoteVersion.specifications.map(e => {
+        return {
+          id: this.makeURLSafeID((e.id || e.name).toLowerCase()),
+          name: e.name,
+          url: `/api/proxy?url=${encodeURIComponent(e.url)}`
+        }
+      })
+      versions.push({
+        id: versionId,
+        name: remoteVersion.name,
+        specifications,
+        isDefault: false
+      })
+      versionIds.push(baseVersionId)
+    }
+    return versions
+  }
+  
+  private sortVersions(versions: Version[], defaultBranchName: string): Version[] {
+    const candidateDefaultBranches = [
+      defaultBranchName, "main", "master", "develop", "development", "trunk"
+    ]
+    // Reverse them so the top-priority branches end up at the top of the list.
+    .reverse()
+    const copiedVersions = [...versions].sort((a, b) => {
+      return a.name.localeCompare(b.name)
+    })
+    // Move the top-priority branches to the top of the list.
+    for (const candidateDefaultBranch of candidateDefaultBranches) {
+      const defaultBranchIndex = copiedVersions.findIndex(version => {
+        return version.name === candidateDefaultBranch
+      })
+      if (defaultBranchIndex !== -1) {
+        const branchVersion = copiedVersions[defaultBranchIndex]
+        copiedVersions.splice(defaultBranchIndex, 1)
+        copiedVersions.splice(0, 0, branchVersion)
+      }
+    }
+    return copiedVersions
+  }
+  
+  private makeURLSafeID(str: string): string {
+    return str
+      .replace(/ /g, "-")
+      .replace(/[^A-Za-z0-9-]/g, "")
+  }
 }
diff --git a/src/features/projects/domain/IProjectConfig.ts b/src/features/projects/domain/IProjectConfig.ts
index 3dc32a0e..7f047f19 100644
--- a/src/features/projects/domain/IProjectConfig.ts
+++ b/src/features/projects/domain/IProjectConfig.ts
@@ -1,4 +1,17 @@
+export type ProjectConfigRemoteVersion = {
+  readonly id?: string
+  readonly name: string
+  readonly specifications: ProjectConfigRemoteSpecification[]
+}
+
+export type ProjectConfigRemoteSpecification = {
+  readonly id?: string
+  readonly name: string
+  readonly url: string
+}
+
 export default interface IProjectConfig {
   readonly name?: string
   readonly image?: string
+  readonly remoteVersions?: ProjectConfigRemoteVersion[]
 }
diff --git a/src/features/projects/domain/getSelection.ts b/src/features/projects/domain/getSelection.ts
index 307f6b7c..b76559ad 100644
--- a/src/features/projects/domain/getSelection.ts
+++ b/src/features/projects/domain/getSelection.ts
@@ -30,8 +30,24 @@ export default function getSelection({
     return {}
   }
   let version: Version | undefined
+  let didMoveSpecificationIdToVersionId = false
   if (versionId) {
     version = project.versions.find(e => e.id == versionId)
+    if (!version && specificationId && !isSpecificationIdFilename(specificationId)) {
+      // With the introduction of remote versions that are specified in the .shape-docs.yml
+      // configuration file, it has become impossible to tell if the last component in a URL
+      // is the specification ID or if it belongs to the version ID. Previously, we required
+      // specification IDs to end with either ".yml" or ".yaml" but that no longer makes
+      // sense when users can define versions.
+      // Instead we assume that the last component is the specification ID but if we cannot
+      // find a version with what we then believe to be the version ID, then we attempt to
+      // finding a version with the ID `{versionId}/{specificationId}` and if that succeeds,
+      // we select the first specification in that version by flagging that the ID of the
+      // specification is considered part of the version ID.
+      const longId = [versionId, specificationId].join("/")
+      version = project.versions.find(e => e.id == longId)
+      didMoveSpecificationIdToVersionId = version != undefined
+    }
   } else if (project.versions.length > 0) {
     version = project.versions[0]
   }
@@ -39,7 +55,7 @@ export default function getSelection({
     return { project }
   }
   let specification: OpenApiSpecification | undefined
-  if (specificationId) {
+  if (specificationId && !didMoveSpecificationIdToVersionId) {
     specification = version.specifications.find(e => e.id == specificationId)
   } else if (version.specifications.length > 0) {
     specification = version.specifications[0]
@@ -65,3 +81,7 @@ function guessSelection(pathname: string) {
     return { projectId, versionId, specificationId }
   }
 }
+
+function isSpecificationIdFilename(specificationId: string): boolean {
+  return specificationId.endsWith(".yml") || specificationId.endsWith(".yaml")
+}
diff --git a/src/features/projects/domain/index.ts b/src/features/projects/domain/index.ts
index 240996ef..bfce5ee2 100644
--- a/src/features/projects/domain/index.ts
+++ b/src/features/projects/domain/index.ts
@@ -1,6 +1,7 @@
 export { default as CachingProjectDataSource } from "./CachingProjectDataSource"
 export { default as getSelection } from "./getSelection"
 export type { default as IProjectConfig } from "./IProjectConfig"
+export * from "./IProjectConfig"
 export type { default as IProjectDataSource } from "./IProjectDataSource"
 export type { default as OpenApiSpecification } from "./OpenApiSpecification"
 export type { default as Project } from "./Project"