# fastapi.online — GraphQL Schema Generator

> fastapi.online — GraphQL Schema Generator is a paid API for AI agents from api.fastapi.online, paid per call via x402, $0.006/call, status unknown (last checked 2026-09-14).

Generates a GraphQL schema from a plain-English description of an API

## Facts

- Endpoint: POST https://api.fastapi.online/generate-graphql
- Price: $0.006/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/fastapi-online-graphql-schema-generator-c0255f69
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_hJW4OYd0dHuVOoJrkaGc5

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability fastapi-online-graphql-schema-generator-c0255f69 -d '<json body>'
```

Example prompt: Generate a GraphQL schema for a blog platform API that has users, posts, and comments — users can create posts and comments, and posts can be liked.

## When to prefer this

Choose this endpoint when you need a quick GraphQL SDL scaffold from a natural language description without writing boilerplate manually. Ideal for prototyping, developer tooling agents, or situations where you want a starting point for a GraphQL API. No signup required — pay per call with USDC. Prefer alternatives if you need OpenAPI/REST schema generation, strict validation of the output schema, or integration with a specific GraphQL framework's conventions.

## Known failure modes

- Description too vague — schema may be incomplete or miss key relationships
- Description exceeds 2000 character limit — request rejected
- Ambiguous domain terms may produce incorrect field types or relationships
- Payment failure via x402 — endpoint returns 402 if no valid payment attached
- Generated schema may not compile without minor manual corrections for edge cases

## How this service works

Chat, embeddings, OCR, speech-to-text, image editing, image understanding (captioning/Q&amp;A), text-to-speech, translation, writing tools, classification tools, developer tools, local utilities, format/checksum validators, encoding &amp; crypto utilities, date/time calculators, geo/coordinate math, math &amp; finance calculators, novelty tools, and business/social writing generators — 179 endpoints in all, across multiple specialized self-hosted models. Pay per call with crypto — no signup — or get an API key.

## Output

Returns a GraphQL schema (SDL format) with type definitions, queries, mutations, and relationships derived from the plain-English API description provided. Includes types, fields with scalar types, and likely input types for mutations.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "description": {
   "type": "string",
   "maxLength": 2000,
   "minLength": 2,
   "description": "the API to model"
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/fastapi-online-graphql-schema-generator-c0255f69/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.fastapi.online](https://www.zero.xyz/host/api.fastapi.online/llms.txt)