diffr

Compare two directories or files. See what changed, what was added, and what was removed.

By default diffr opens a local web UI. You can also print a unified diff, write a patch, or emit JSON for scripts and CI.

Install

Homebrew (macOS / Linux)

brew install imrajdas/tap/diffr

diffr version

Upgrade later with:

brew upgrade imrajdas/tap/diffr

The fully qualified name (imrajdas/tap/diffr) taps this repo and trusts only this cask. Equivalent two-step form:

brew tap imrajdas/tap
brew install diffr

GitHub Releases

Grab the archive for your OS from Releases.

Linux / macOS

tar -zxvf diffr_*_*.tar.gz
chmod +x diffr
sudo mv diffr /usr/local/bin/diffr
diffr version

Windows — unzip the archive and run diffr.exe version.

From source

Needs Go 1.26.6 or later.

go install github.com/imrajdas/diffr@latest

Or clone and build:

git clone https://github.com/imrajdas/diffr
cd diffr
go build -o diffr .

Quick start

# Open a side-by-side view in the browser
diffr ./old ./new

# Compare two files
diffr ./old.txt ./new.txt

# Print a unified diff (like diff -r)
diffr ./old ./new --stdout

# JSON for CI
diffr ./old ./new --json

# Write a patch
diffr ./old ./new --patch changes.patch

Without --stdout, --json, or --patch, diffr serves http://localhost:8675 and opens it in your browser. Use --no-open if you only want the server.

Try the bundled demo trees from this repo:

diffr testdata/demo/left testdata/demo/right

What it compares

diffr walks both trees:

Status	Meaning
changed	Present on both sides, content differs
added	Only in the right tree
removed	Only in the left tree
identical	Counted, not listed

File types are handled separately:

Text — unified diffs, side-by-side in the UI
Images (PNG, JPEG, GIF) — pixel comparison with a left/right slider
PDFs — page count and extracted text
Binaries — size/hash comparison, never dumped as text

The web UI also has a summary bar, filters (name, extension, status), unified vs side-by-side, and dark mode.

Ignore rules

By default diffr skips .git, node_modules, __pycache__, .svn, .hg, .DS_Store, and Thumbs.db.

Rules are applied in this order:

Built-in excludes (unless --no-default-exclude)
.diffrignore in the current directory and at the root of each tree (gitignore syntax)
.gitignore from the git root of each tree (unless --no-gitignore)
--exclude / -e patterns (repeatable)
--ignore-file for an extra ignore file

Example .diffrignore:

*.log
dist/
vendor/

Flags

diffr [dir1/file1] [dir2/file2] [flags]
diffr version

Flag	Description
`-a, --address string`	Bind address for the web server. Default: `http://localhost`
`-p, --port int`	Port. Default: `8675`
`--stdout`	Print a unified diff instead of starting the web UI
`--json`	Print a JSON report instead of starting the web UI
`--patch string`	Write a unified patch (`-` for stdout) instead of starting the web UI
`--no-open`	Do not open a browser
`-C, --context int`	Unified-diff context lines. Default: `3`
`-w, --ignore-whitespace`	Ignore files that differ only in whitespace
`-i, --ignore-case`	Ignore files that differ only in case
`-e, --exclude stringArray`	Gitignore-style glob to exclude (repeatable)
`--ignore-file string`	Extra `.diffrignore` file
`--no-default-exclude`	Skip built-in excludes
`--no-gitignore`	Do not apply `.gitignore`

--stdout is colored when stdout is a TTY. Set NO_COLOR=1 for plain text. --patch files are always uncolored.

# UI on all interfaces, no browser
diffr ./old ./new -a 0.0.0.0 -p 9000 --no-open

# Ignore whitespace-only changes and extra paths
diffr ./old ./new --stdout -w -e '*.log' -e vendor

Exit codes

Used with --stdout, --json, or --patch:

Code	Meaning
`0`	No differences
`1`	Differences found
`2`	Error

Contributing

Bugs and ideas: open an issue. Code: fork and send a pull request.

License

Apache License 2.0

imrajdas/diffr

README