Compare Code From Two Git Branches — Free Online Method

Git has built-in diff for comparing branches: git diff branch1..branch2 gives you the unified diff between two branches. But unified diff format is dense, and comparing a specific function across branches is difficult when the diff includes dozens of other changed files.

For targeted cross-branch comparison, extracting the function from each branch and diffing it in a browser tool like Raven Code Diff gives you a cleaner, more readable result. Here's how.

Git's Built-In Diff vs Targeted Function Comparison

Git diff for branch comparison:

• git diff main..feature-branch — shows all changes between two branches
• git diff main..feature-branch -- path/to/file.py — scoped to one file
• git show main:path/to/file.py — shows the file as it exists in the main branch

These commands work well when you want the full picture. But for comparing a specific function across branches — especially in large files where git diff shows too much context — a targeted extraction and paste is faster to reason about.

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How to Extract and Compare a Function From Two Branches

Step-by-step:

1. View the function in branch A: git show main:src/utils.py | grep -A 30 "def process_data" — this shows 30 lines of the function starting from its definition in main
2. Copy the output to a temp note
3. Repeat for branch B: git show feature-branch:src/utils.py | grep -A 30 "def process_data"
4. Paste both versions into Raven Code Diff — original on left, branch B version on right
5. Select your language and click Compare

You get a clean, focused diff of just that function, with syntax highlighting, line numbers, and color coding — without the noise of the full branch diff.

When to Use This Approach vs Standard git diff

Use git diff branch1..branch2 when: You want the full picture — all files changed, all functions, in one view. This is the right tool for a comprehensive branch comparison.

Use the extract-and-paste method when:

• You're focused on one specific function and don't want the noise of the full diff
• The file is large and git diff context is hard to navigate
• You want syntax highlighting beyond what your terminal provides
• You're sharing the comparison with someone who doesn't have git access
• You're comparing on a machine without git installed (e.g., a production server you've SSH'd into)

Both approaches belong in a developer's workflow. Terminal git diff for comprehensive analysis; browser diff for targeted, readable comparisons.

Frequently Asked Questions

How do I compare two branches in git?

Use "git diff branch1..branch2" to see all changes between two branches. Add "-- path/to/file" to scope it to a specific file. Use "git show branch:path/to/file" to see the full file content as it exists in a specific branch.

How do I compare a specific function between two git branches?

Run "git show branch1:file.py" and "git show branch2:file.py" to get both versions, extract the function from each output, then paste both into Raven Code Diff. You get a focused diff of just that function with syntax highlighting.