Stop Diffing Text, Start Diffing Logic.
AI is generating more code than ever. PRs are getting larger, way more structurally complex, and line-based diffs can't keep up. You move a function three functions down and git diff shows it as a delete + re-add. You rename a variable and suddenly dozens of lines light up red and green. The actual Change is buried.
diffmantic parses your code into ASTs using Tree-sitter and computes structural differences. It knows when a function was Moved, not deleted and re-added. It shows you exactly what changed inside a node, a variable rename, a swapped argument, an updated string literal, instead of highlighting entire lines.
It works as a standalone CLI, a drop-in for git diff, or a backend for editor plugins via JSON output.
- Move Detection. When you move a function or a block, diffmantic tracks it as a Move. Not a delete + re-add. Moved functions, blocks, and statements are all first-class.
- Update & Rename Detection. Shows exactly what changed inside a syntax node. A variable rename, a string literal swap, a type change, you see the precise edit, not a wall of red and green.
- Git Integration. Run
diffmin any Git repo and it launches an interactive TUI. Browse modified files, stage/unstage changes, commit, all without leaving the terminal. - Interactive TUI. Side-by-side diff view with syntax highlighting, code folding, search, and jump-to-move-counterpart. Built with Bubbletea and Lipgloss.
- JSON Output. Stable schema with child-index paths (e.g.,
[0, 2, 1]) instead of line numbers. So editor plugins can keep highlights intact even as you edit the file. - 4 Core Languages. Go, Python, JavaScript, TypeScript. Full AST normalization and matching rules powered by Tree-sitter.
| Language | Extensions |
|---|---|
| Go | .go |
| Python | .py |
| JavaScript | .js .jsx .mjs .cjs |
| TypeScript | .ts .tsx .mts .cts |
curl -fsSL https://raw.githubusercontent.com/HarshK97/diffmantic/main/install.sh | shThis installs the diffm binary to ~/.local/bin. Make sure it's in your $PATH.
It auto-detects your OS and architecture, grabs the right binary from GitHub Releases, and verifies the SHA256 checksum.
# Install to a specific directory
curl -fsSL https://raw.githubusercontent.com/HarshK97/diffmantic/main/install.sh | sh -s -- --dir=/usr/local/bin
# Install a specific version
curl -fsSL https://raw.githubusercontent.com/HarshK97/diffmantic/main/install.sh | sh -s -- --version=v0.1.0brew install HarshK97/tap/diffmanticPrebuilt binaries for Linux, macOS, and Windows (amd64 + arm64) are on the Releases page.
Requires Go 1.24+. No C compiler or CGo required (CGO_ENABLED=0).
git clone https://github.com/HarshK97/diffmantic.git
cd diffmantic
go build -o diffm ./cmd/diffm
# Or install directly with Go:
go install github.com/HarshK97/diffmantic/cmd/diffm@latestBuilt with
gotreesitterfor pure Go Tree-sitter AST parsing with zero C compiler or CGo runtime dependencies.
# Launch the interactive TUI in any Git repository
diffm
# Show only staged changes
diffm --cached# Diff working tree against HEAD
diffm HEAD
# Diff between two commits, tags, or branches
diffm HEAD~1 HEAD
diffm main...feature-branch# Interactive TUI (default when a terminal is attached)
diffm diff before.go after.go
# JSON output for editor plugins and automation
diffm diff before.go after.go -f json
# Human-readable action list
diffm diff before.go after.go -f actions
# Override language detection
diffm diff config.txt config2.txt --lang jsondiffmantic matches ASTs in four phases, based on the GumTree algorithm:
- Top-Down Matching. We look for identical subtrees by height. When we find an exact match, all nodes in the subtree get mapped together.
- Bottom-Up Matching. For unmatched nodes, we look for counterparts of the same type that share already-matched children. If the Dice similarity score is high enough, we match them.
- Recovery. Inside matched containers, we run LCS alignment on unmatched children. First by exact label, then by structural shape.
- Action Generation & Post-Processing. We produce a raw edit script (insert, delete, update, move) and then refine it. Child edits get collapsed into clean subtree operations, comment changes get normalized, and related moves get grouped.
diffmantic.nvim is the Neovim plugin that started this whole project. It currently ships with its own embedded alpha engine and is being migrated to use the diffm CLI as its backend via JSON output.
Planned. The JSON output is built to support editor integration, so if you want to build one, the plumbing is there.
diffm diff -f json outputs a stable v1 schema with child-index paths. Take a look at diffm diff file-a file-b -f json to see the full structure.
MIT. See LICENSE.
The engine is based on the GumTree matching algorithm and the Chawathe edit script generator:
- GumTree: A Complete Approach for AST Differencing, Falleri et al.
- Beyond GumTree, Huvier et al.
- GumTree GitHub Repository