SlickFast

A deterministic render engine. Spec in, same bytes out. Forever. Charts, boards, and whole Pages. No headless browser.

↑ Engine output — one JSON spec, one image. Get this exact board on your README with the dashboard template (teal-hero layout).

Local MCP is free forever. A public URL is a plan (free key is enough to learn).

The spec is the chart. A pagespec is a Page. Add .json — that’s the twin. The hash is on the page. Don’t trust us. Check the math.

• npm (MCP): @slickfast/mcp@0.7.32
• Website: slickfast.com
• Engine explainer (a Page): open it · twin
• Get started / News: slickfast.com/start · slickfast.com/news
• Bugs: GitHub Issues · feedback@slickfast.com

This project's pulse — a LIVE chart, right here in the README

The dashboard below is not a screenshot. It's a SlickFast live chart: a permanent image URL whose numbers update on their own. A scheduled job pushes fresh stats; every visitor sees current data. Live Charts — embed once, update forever.

The range — two boards, two renders

A seller ops board (funnel, bullet graph, goal ring, gauge, calendar heatmap, leaderboard — demo data):

And the board that explains the engine — it times its own render into its title:

Prove it yourself

Don't take the speed or determinism claims on faith — run the benchmark on your own machine:

git clone https://github.com/SlickFast/slickfast && cd slickfast
node scripts/bench.mjs

It renders all 47 chart types, times each, runs a 10,000-chart throughput burst, and double-renders everything to verify byte-identical output. On an M1 Max: median 15µs per chart, ~140,000 renders/sec, 47/47 deterministic. Your numbers are your numbers.

Quick start (MCP)

One-click:

Add to your MCP client config (Claude Code, Claude Desktop, Cursor, …):

{
  "mcpServers": {
    "slickfast": {
      "command": "npx",
      "args": ["-y", "@slickfast/mcp"],
      "env": { "SLICKFAST_API_KEY": "SF-…" }
    }
  }
}

Omit env to stay local-only (draw free forever). Add a free key from slickfast.com when you want a live URL, share, or a published Page.

Then: get_started → news → gallery → one render_chart. Full tool docs: apps/mcp/README.md.

How to keep a Page

“Save it” is two jobs. On disk: render_page + keep the pagespec JSON (no key). In the world: publish_page (SF- key) → pages.slickfast.com/s/… + .json twin. The hash is on the page. Find it later with my_pages.

Why agents pick SlickFast

• Deterministic — same spec, same bytes. Cacheable. Testable.
• Cheap tokens — a few dozen tokens of JSON beat hundreds of matplotlib / SVG retries.
• One-field edits — swap type, palette, size; re-render. No code rewrite.
• Pages = shareable memory — agent output → Page → twin → hash on the page. Not stuck in chat.
• No headless browser — pure in-memory SVG → PNG (and Page HTML).
• 47 types + tiled dashboards in one call.
• Loud errors — bad enum / unknown palette lists the valid options.
• Local by default — nothing phones home from the MCP package.

What's in this repo

Path	What it is
packages/render-core/	The engine: pure (spec) → SVG string. All 47 types, the type registry, SPEC.md (the spec contract), examples, gallery, and the golden snapshot net.
packages/palette-core/	The color library: palettes, nested themes, WCAG contrast, tokens.
packages/raster/	SVG → PNG rasterization (resvg).
packages/fonts/	The swappable font layer.
apps/mcp/	The MCP server published as @slickfast/mcp — a thin surface over the engine.
apps/api/	The hosted HTTP API — API.md is the how-to-call-it guide (no MCP needed: curl, <img src>, any language), openapi.yaml the machine-readable contract. Live at api.slickfast.com; free tier at slickfast.com.
scripts/	The safety net: golden checks, registry-drift check, 323-case torture suite, palette hex check.
templates/	Ready-made spec presets.

Build & verify from source

cd apps/mcp && npm install && npm run build     # builds dist/index.js
cd ../../packages/raster && npm install          # native resvg binding (PNG)

# from the repo root — the full safety net:
node packages/render-core/generate.mjs --check   # golden snapshots (all types)
node scripts/check-surfaces.mjs                  # type-registry drift check
node scripts/torture.mjs                         # 323 empty/edge-case renders
node scripts/check-palettes.mjs                  # palette hex validation

The engine is pure and deterministic by contract: no IO, no Date.now(), no Math.random() in drawing code, and nothing ships without a snapshot test.

Contributing

• Bug reports and feature requests are the best way to contribute — please use the issue templates. The MCP's built-in report_issue tool writes a ready-to-paste report for you.
• Day-to-day development happens in an internal tree and releases are published here, so a PR may be ported in rather than merged directly — you'll be credited either way. For anything non-trivial, open an issue first so we can agree on the shape.

License

AGPL-3.0-only. Local MCP is free. Closed commercial products (embed or self-host without AGPL) need a commercial license from $99/year: slickfast.com/license.html · licensing@slickfast.com. Hosted API / hosted MCP: slickfast.com/#pricing.