GitUsing Merge Tools

Using Merge Tools

A merge tool is a graphical (or TUI) program that helps you resolve conflicts by showing the two sides side-by-side and letting you pick hunks with a click instead of editing raw conflict markers. Git ships with git mergetool to launch the configured tool for each conflicted file.

Why use a merge tool

  • Three-way view — see base, ours, and theirs at the same time. Much clearer than reading markers.

  • Click to take a side — no risk of accidentally leaving <<< in the file.

  • Syntax highlighting — easier to read code than plain text.

  • Inline editing — fix typos and refactor right in the merge view.

Popular merge tools

  • VS Code — built-in 3-way merge editor (Open Merge Editor button in Source Control). Free.

  • Meld — free, cross-platform, simple. Popular default on Linux.

  • Beyond Compare — paid, very powerful. Industry favourite.

  • P4Merge — free part of Perforce. Solid 3-way view.

  • KDiff3 — free, open-source, cross-platform.

  • Kaleidoscope — Mac-only, beautiful, paid.

  • vimdiff / Neovim — terminal-based, no install needed if you already use Vim.

Configuring a merge tool

VS Code

Bash
git config --global merge.tool vscode
git config --global mergetool.vscode.cmd 'code --wait --merge $REMOTE $LOCAL $BASE $MERGED'
git config --global mergetool.keepBackup false

Meld

Bash
git config --global merge.tool meld
# Meld is auto-discovered on most installs

vimdiff

Bash
git config --global merge.tool vimdiff
git config --global mergetool.vimdiff.cmd 'vimdiff $LOCAL $MERGED $REMOTE'

Beyond Compare

Bash
git config --global merge.tool bc4
git config --global mergetool.bc4.path '/Applications/Beyond Compare.app/Contents/MacOS/bcomp'  # macOS
Launching the tool

During a merge with conflicts

Bash
git merge feature-x          # produces conflicts
git mergetool                # opens the merge tool for each conflict
# Resolve in the GUI, save, close.
# Repeat for each conflicted file.
git commit                   # finalise the merge
The four files the tool sees

  • $BASE — the common ancestor (where the two branches diverged).

  • $LOCAL — your side (the branch you were on before merging).

  • $REMOTE — their side (the branch being merged in).

  • $MERGED — the file Git wants you to produce. Edit this one — it becomes the final content.

VS Code merge editor walkthrough

  • Open the Source Control panel (Ctrl/Cmd + Shift + G).

  • Click a conflicted file. The “Open in Merge Editor” button appears at the top.

  • You see three panes: Incoming (theirs), Current (ours), and Result.

  • Each conflict has buttons: “Accept Current”, “Accept Incoming”, “Accept Both”.

  • Edit the Result freely. When done, click “Complete Merge”.

  • Stage and commit as usual.

Avoiding backup files

By default mergetool keeps .orig backups

Bash
# Resolve a conflict in src/app.js — Git creates src/app.js.orig

# To turn this off:
git config --global mergetool.keepBackup false
Cleaning up .orig files

Bash
find . -name "*.orig" -delete
# Or add *.orig to your global .gitignore_global
Triggering the tool for a single file

Bash
git mergetool -- path/to/specific-file.js
Using a tool that you already have configured

Override the configured tool for one merge

Bash
git mergetool --tool=meld
List supported tools

Bash
git mergetool --tool-help
# Lists every tool Git knows about + which ones are detected on your system
No tool? Edit the file directly.
You do not *need* a merge tool. Many experienced developers just resolve conflicts in their normal editor with the conflict markers visible. Tools shine on big, complex merges; small conflicts are often easier without them.
Tip
Set up your merge tool **once** when you install Git. Then you never have to think about it again — `git mergetool` just works whenever you need it.