Transitions.dev

Why it's ranked here

The free layer is useful on its own terms. Each copied snippet bundles its own variables, scoped class names and a reduced-motion guard, so it drops into any project without the demo's markup. The scanner is deterministic, runs with no account, and the GitHub Action can post a score on every pull request or block merges below a threshold. The weight against it is commercial: the most capable fixing paths sit behind a hosted service and paid plans, and the agent skill itself tells assistants not to fix motion by hand.

What's good

The scanner reads design tokens rather than only literal values, so a transition that looks fine but points at a three-second variable is still flagged as slow. Per-rule penalty caps stop one noisy rule from zeroing the score, and suggestions for components the library covers carry no penalty at all. Fixes are review-first: diffs are shown before anything is written, pull requests go to a new branch and never to main, and the fix modes promise to touch motion only, never component logic. Fixes written with library tokens also carry the raw value as a fallback, so an undefined token cannot silently switch a transition off.

Tradeoffs

Two licenses apply. The tooling is MIT, but the transitions themselves come under a custom license that forbids redistributing them as a competing library, and the branding is all rights reserved. Hosted fixes need a license key and send your affected files to the vendor's service, which calls Claude with its own key; the free tier allows 10 polish fixes a month and 2 a day. Revamp mode and Pro recipes need the Business plan at $59 a month, and running fixes in CI on your own model keys needs Enterprise. Refine is labelled early Beta and spends your own agent credits on every click.

How to use it well

Start with the free path: copy snippets from the site or pull them with the installer, and keep the shared timing variables so the whole app moves on one scale. Add the scanner's GitHub Action with a minimum score as a motion lint that needs no license and makes no AI calls. If you want automated fixes but not the hosted service, connect the MCP server to your own Claude, which exposes the scan contract and recipe sources. Teams should check the plan rules first: any company use of Pro recipes or paid agent features needs a Business seat, even for one designer.

Observed

License (tooling)

MIT for the agent, CLI, Refine, build and scripts directories (LICENSE section 2)

License (transitions and skills)

Custom Transitions.dev license: free commercial use, no redistribution as a competing library

Language

JavaScript ES modules, Node 18 or newer per package engines

Packages

npm: transitions-dev (CLI), transitions-agent (scanner), transitions-refine (Refine panel)

Interfaces

CLI, agent skill, GitHub composite Action, hosted MCP server over HTTP

Agent skill targets

Claude Code, Cursor, Codex named in README and LICENSE

Hosted dependency

Hosted fixes and Pro recipes come from api.transitions.dev and need a license key or sign-in

Tests

transitions-agent declares a node --test script; no test files were in the fetched set

Root package

Private, single build script that regenerates the skill from the showcase page