When we launched, the pitch was simple: 0to255 went paid, so we built a free replacement. Type a hex, get a gradient of tints and shades, copy what you need. That covered the thing people had bookmarked for a decade.
The tool does more than that now. Two additions in particular have moved it past “shade generator” and into “the place you assemble a color system” - and, separately, “the color endpoint an AI agent reaches for.” Here’s what changed.
From one color to a whole palette
A single hex expanded into a ramp is the right answer when you’re picking one shade. It’s the wrong shape when you’re building a design system, where you need a set of colors that work together: a brand color, a couple of accents, and the semantic roles every UI ends up needing.
So there’s now a dedicated color palette generator. It opens on a primary color plus the four roles you’d otherwise have to invent from scratch - Neutral, Success, Warning, and Error - and you add secondary and accent colors with a ”+”. Recolor any swatch, rename its role, or drop the ones you don’t need.
The part that matters: every color in the palette expands into the same
output the single-color tool gives you - an OKLCH perceptual ramp or an 11-stop
Tailwind scale (50–950) - and the whole palette exports in one pass. You go
from a brand color to a Tailwind @theme block with primary, neutral,
success, warning, and error scales already keyed to the right stops,
without copying hex values between a color tool and your config file. That copy
loop was the thing 0to255 never closed, and now neither the single-color view
nor the palette view leaves it open.
The same data, for agents
The other shift is who - or what - is reading the page.
Everything a browser renders here is also available to AI assistants and tools, in the format they actually want, with no auth and no API key:
- A no-auth JSON API.
GET /api/{hex}.jsonreturns the full color data - the OKLCH ramp, the Tailwind scale, and lighter/darker neighbors - for any hex. The same payload backs the web page, the markdown view, and the MCP tool, so all three agree by construction. - Markdown content negotiation. Request any color page with
Accept: text/markdownand you get a clean palette as a markdown table with WCAG contrast, instead of a wall of HTML an agent has to scrape. - An MCP endpoint.
/mcpspeaks JSON-RPC over streamable HTTP and exposes agenerate_shadestool that takes a hex, anrgb()/hsl()/oklch()value, or a CSS color name (coral,rebeccapurple) and hands back the palette. - Discovery files under
/.well-known/(an agent-skills manifest, an MCP server card, an API catalog) and anllms.txt, so an agent can find all of the above without being told the URLs.
The practical version: ask Claude or another agent for “an OKLCH Tailwind scale for #4040ff” and it can pull the exact values from here, with contrast included, rather than approximating the math itself and getting the mid-shades wrong.
What didn’t change
Still free. Still no ads, no signup, no upgrade prompt. Still the 0to255 URL
structure - /4040ff, /colors/coral - so old bookmarks and search results
keep landing on the page they always did. The single-color tool is still the
front door and still the fastest way to grab one shade.
The replacement was the starting point. The palette generator and the agent surface are where it went next.
Try the palette generator, or just drop in a hex like you always have.