A meld-flavored side-by-side diff and merge tool that renders in a Chrome app
window. Vanilla JS/CSS/SVG, no build step. The Go binary is the long-running
process: it serves the UI, and when you resolve a merge it writes the result
back and exits — so it drops straight into git mergetool.
Resolving a conflict (theirs chosen — the un-kept side dims, intra-line change highlighted):
- Merge mode — reads a git-conflicted file, parses
<<<<<<< ======= >>>>>>>markers (2-way and diff3), shows ours/theirs side by side. Pick per conflict: ours / theirs / both↓ / both↑ / base / skip, hit Merge & Apply. The binary reassembles the file, writes it, exits 0. - Diff mode — side-by-side diff of two files.
- Branch + filename labels in the headers, dual line-number gutters.
- Colorized diff with intra-line char highlighting (the changed substring inside a line, meld-style) via Myers diff.
- Syntax highlighting (highlight.js), light / dark theme (auto-detects, toggle).
- Fonts: Inter (UI), JetBrains Mono / SUSE Mono (code).
A diff tool shouldn't drag in a supply chain.
- No npm, no Python, no
node_modules. Vanilla JS in the browser, a Go binary on the host. Nothing installs at runtime. - One dependency.
sergi/go-diff, pinned by hash ingo.sum. That's the whole tree. - Supply-chain surface ≈ zero. The recent npm attacks ride deep dependency trees and malicious postinstall scripts. gdf has neither. Nothing to poison.
- Single static binary. No runtime, no interpreter. Build once, run anywhere — linux / mac / windows, amd64 / arm64.
- Reproducible. Same source, same
go.sum, same bytes. - A webview buys a rich UI for free. Real layout, web fonts, color, SVG, motion — all in vanilla HTML/CSS/JS. No native-widget ceiling. The look is fully yours to shape; customization is endless.
- And I love Go.
Three ways. Pick one.
Grab the archive for your platform from the latest release, verify, run:
# example: linux/amd64
tar -xzf gdf_v1.0.3_linux_amd64.tar.gz
install -Dm755 gdf ~/.local/bin/gdf
# verify against the published checksums
sha256sum -c checksums.txt --ignore-missingWindows ships a .zip; macOS uses the darwin archives. Each release carries
checksums.txt (sha256) covering every asset.
The macOS binaries are unsigned, so Gatekeeper quarantines them on first run. Clear it once:
xattr -d com.apple.quarantine gdf # or: right-click -> Opengo install github.com/mbarlow/gdf@latest # -> $(go env GOPATH)/bin/gdfgo install replaced go get for installing binaries (Go 1.17+).
@latest resolves to the newest semver tag.
make install # -> ~/.local/bin/gdf (stamps version from git describe)Requires Go 1.25+. At runtime gdf needs a Chromium-family browser on PATH
(google-chrome, chromium, brave, edge). gdf --version prints the build.
make install # -> ~/.local/bin/gdfRequires Go 1.25+ and a Chromium-family browser on PATH (google-chrome, chromium, brave, edge).
gdf merge <conflicted-file> # resolve conflict markers, write back
gdf diff <fileA> <fileB> # side-by-side diff
gdf <fileA> <fileB> # alias for diff
gdf git [<rev>] # working tree vs HEAD (or <rev>), all files
gdf git --staged [<rev>] # index vs HEAD, all files
# flags (anywhere on the line):
# --theme light|dark|auto default auto
# --port N fixed port (default random)
# --no-open print URL instead of launching Chrome
# --lang <id> force syntax language (paths without an extension)
# --staged git mode: diff the index instead of the working tree
# --version print version and exitmake git-config-simpleWires gdf as mergetool + difftool and adds two aliases:
git gd [<rev>] [--staged] # all working changes in one gdf window
git gm <branch> # merge; if it conflicts, gdf opens to resolveYou can't retrain bare git merge / git diff — those are builtins, and git
ignores aliases that shadow them. git gd / git gm are one keystroke off and
do the job. git mergetool and git difftool work too (set by the same target).
make git-config
# or manually:
git config --global mergetool.gdf.cmd 'gdf merge "$MERGED"'
git config --global mergetool.gdf.trustExitCode true
git config --global merge.tool gdf # <- without this, bare `git mergetool`
# falls back to git's built-in list
git mergetool # uses gdf; or force per-run with: git mergetool -t gdfgit mergetool launches gdf once per conflicted file, sequentially — resolve
and close each window before the next opens.
Exit codes: 0 = merged/applied (or diff closed), 1 = aborted (Abort button,
window closed, or Esc). With trustExitCode true, git only marks a path
resolved when gdf exits 0.
Two ways. Both come from make git-config.
gdf git — one window, all changed files, a file-list sidebar. gdf reads
git itself, so the panes are labeled by ref (HEAD vs working tree).
gdf git # working tree vs HEAD
gdf git --staged # index vs HEAD
gdf git <rev> # working tree vs a branch / commit / tagSidebar status badges: M modified, A staged-add, D deleted, R renamed,
U untracked. Untracked files (not ignored) are included and rendered as
all-new. --staged mode skips them — the index can't hold untracked.
git difftool — gdf as git's difftool, one window per changed file
(sequential, like mergetool):
git config --global difftool.gdf.cmd 'gdf diff "$LOCAL" "$REMOTE"'
git config --global diff.tool gdf
git config --global difftool.prompt false
git difftool # unstaged vs HEAD
git difftool --cached # staged vs HEAD
git difftool <rev> # working vs a refgdf git is usually what you want; git difftool plugs into existing muscle
memory.
Diff mode takes any two files, so pair it with git show and process
substitution to compare a path across branches, commits, or working tree:
# same file on two branches (--lang because /dev/fd/* has no extension)
gdf diff --lang python <(git show main:app.py) <(git show feature/refresh:app.py)
# working tree vs HEAD (right side is a real path, so it picks up .py itself)
gdf diff <(git show HEAD:app.py) app.py --lang python
# any two commits
gdf diff --lang json <(git show abc123:config.json) <(git show def456:config.json)Process substitution (<(...)) feeds gdf opaque /dev/fd/* paths, so the pane
headers show those and syntax highlighting can't infer the language — pass
--lang to force it.
Ctrl/Cmd+Enter— Merge & Apply (when all conflicts resolved)Esc— Abort
git mergetool ──► gdf merge $MERGED ──► HTTP server on 127.0.0.1:rand
│
Chrome --app ◄──┘ (frameless app window)
│
you pick choices ──► POST /api/resolve ─► reassemble ─► write $MERGED ─► exit 0
The conflicted file is the source of truth: gdf splits it into literal segments and conflict regions, renders the regions, and on resolve stitches the literal text back together with your chosen blocks. No reliance on separate LOCAL/BASE/REMOTE temp files — branch labels come from the markers themselves.
gdf is MIT.
The one Go dependency, sergi/go-diff, is MIT. It's a port of Google's diff-match-patch, which is Apache-2.0, so go-diff carries both notices — retained in the distributed binaries (see NOTICE). Both are permissive; no copyleft reaches gdf.