syndiff

syndiff is a lightweight, standalone library that implements a structural diff algorithm inspired by Difftastic, designed to be embedded inside other tools and applications.

It compares code as syntax, not just text - producing diffs that align with how developers reason about changes.

✦ Key features

• Structural diffing - compares syntax trees, not text lines
• Embeddable by design - a library core, no CLI or UI assumptions
• Language-agnostic - parsing is external; the algorithm is generic
• Deterministic output - stable, predictable diffs for tooling
• Minimal API - small surface area, easy to integrate and experiment

✦ Philosophy

Traditional diffs treat code as text. Syndiff treats code as having shape.

This library exists to make syntax-aware diffing easy to integrate into editors, code review tools, language servers, and research projects - without dragging along a full application.

It does not aim to replace Difftastic. It distills its core ideas into a reusable form.

✦ Inspiration

Inspired by Difftastic, created by Wilfred Hughes. All credit for the original algorithmic ideas belongs there. Any bugs introduced here are new and entirely our own.