I Built 1,000 Utility APIs for AI Agents with Cloudflare Workers and x402 🌸

Koyori Utils API — Mon, 12 Oct 2026 22:47:42 +0000

Update — October 14, 2026: Koyori Utils API has grown from 300 to 1,000 endpoints! This article has been updated to reflect the latest release, redesigned website, and testing progress.

What started as a small collection of developer utilities has grown into Koyori Utils API — a service offering 1,000 utility endpoints for developers and AI agents. 🚀

The goal is simple: provide practical, focused tools through a single service, without requiring a monthly subscription.

And now, the project has a brand-new cherry blossom-themed homepage! 🌸🐱

🌸 What's new in the 1,000-API release?

Since reaching 300 endpoints, I've added another 700 utilities and significantly improved the experience of discovering them.

The latest version includes:

1,000 utility endpoints for common development and automation tasks.
A completely redesigned homepage with a soft sakura-inspired theme.
Searchable API directory to quickly find useful operations.
Category navigation for exploring available tools.
Featured Tools highlighting selected utilities.
OpenAPI documentation for machine-readable API discovery.
AI-friendly resources including llms.txt and metadata.json.
x402 payment protection on Stacks mainnet.

The new interface even features a fluffy white cat sleeping among cherry blossoms.

Explore the live website:

https://koyori-utils-api.koyori-aibtc.workers.dev

🛠️ What can you do with 1,000 utility APIs?

The collection covers many everyday programming and data-processing tasks.

Text utilities

Manipulate strings, clean up whitespace, analyze words, extract information, and transform text.

JSON and object utilities

Format JSON, inspect objects, extract properties, and transform structured data.

Array utilities

Remove duplicates, filter values, rotate arrays, flatten collections, and perform other common operations.

Math and number utilities

Calculate averages, distances, ratios, rounding results, and other numerical transformations.

Date and time utilities

Parse dates, manipulate timestamps, and perform date-related operations.

AI agent utilities

Analyze message lists, inspect roles, count messages, and process data used in automated agent workflows.

Instead of writing and deploying a separate service for each small operation, developers and AI agents can discover available utilities through one API collection.

🤖 Designed for AI agents

One of the main goals is to make API tools easier for autonomous systems to discover.

Koyori Utils API provides machine-readable resources, including:

OpenAPI specifications
llms.txt
metadata.json

These resources help developers and agents explore available operations and their interfaces.

For AI agents that perform many small data-processing tasks, a searchable utility collection can be a convenient building block.

⚡ Built with Cloudflare Workers, Hono, and TypeScript

The technology stack includes:

Cloudflare Workers — serverless deployment at the edge.
Hono — lightweight API routing.
TypeScript — application development and type checking.
Stacks mainnet — the blockchain network used for the payment integration.
x402 — HTTP-based payment-required flow.
OpenAPI — machine-readable endpoint definitions.

The service is designed around small, focused API operations that can be called individually.

💰 Pay per request with x402

The listed price for a paid API request is:

0.001 STX per request

There is no monthly subscription requirement for the intended pay-per-request model.

For example, the API directory includes:

POST /api/plus-text-word-lengths

This endpoint calculates the character lengths of whitespace-separated words.

A basic request without a payment payload looks like this:

curl -i -X POST \
  "https://koyori-utils-api.koyori-aibtc.workers.dev/api/plus-text-word-lengths" \
  -H "Content-Type: application/json" \
  -d '{"text":"hello world"}'

Since the endpoint is payment-protected, a request without valid payment information is expected to receive:

HTTP 402 Payment Required

Current verification status: An unpaid production request to this newly added endpoint returned HTTP 402 as expected. Successful end-to-end STX settlement, authenticated paid execution, and revenue generation have not yet been verified.

These are important next steps, and I want to be transparent about what has and hasn't been tested.

🧪 How I expanded from 300 to 1,000 endpoints

Growing the project has also meant improving the development process.

The workflow includes:

Preparing new batches of utility endpoints.
Checking for duplicate API paths.
Updating homepage cards and API documentation.
Creating backups before modifying source files.
Running TypeScript checks.
Running offline functional tests.
Deploying to Cloudflare Workers.
Verifying production homepage and documentation counts.

For the latest batch of 100 endpoints, the offline functional tests reported:

100 passed / 0 failed

Production verification also reported:

1,000 homepage API cards / 1,000 OpenAPI routes

These checks are useful milestones, although they don't replace complete end-to-end testing of every paid operation.

🌸 A new homepage for a growing API collection

With 1,000 endpoints, usability becomes especially important.

The redesigned homepage includes a large search field, category navigation, endpoint cards, featured utilities, documentation links, and convenient URL-copy controls.

The sakura-themed design brings a more welcoming personality to what would otherwise be a very technical API directory.

🔗 Try Koyori Utils API

Website

https://koyori-utils-api.koyori-aibtc.workers.dev

OpenAPI documentation

https://koyori-utils-api.koyori-aibtc.workers.dev/openapi.json

GitHub

https://github.com/sophiaalice0913-cmyk/koyori-utils-api

The project is still evolving, and there's plenty more work ahead: validating real payments, improving documentation, testing actual agent integrations, and learning which utilities developers find most valuable.

💬 Feedback welcome!

If you're building AI agents, automation tools, or developer workflows, I'd love to hear your thoughts.

What utility API would make your development workflow easier?

And if you have a chance to explore Koyori Utils API, feedback on the endpoint collection, documentation, or user interface would be greatly appreciated.

Thanks for following the journey from 300 to 1,000 utility APIs! 🌸🐱

DEV Community: Koyori Utils API