# fastapi.online — Environment Variable Documentation Generator

> fastapi.online — Environment Variable Documentation Generator is a paid API for AI agents from api.fastapi.online, paid per call via x402, $0.001/call, status unknown (last checked 2026-09-14).

Generates human-readable documentation for a set of environment variables provided as a string.

## Facts

- Endpoint: POST https://api.fastapi.online/env-doc-generate
- Price: $0.001/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-environment-variable-documentation-generator-8fd6f8ee
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_jVkruBxgSbNStNX4KPEH2

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-environment-variable-documentation-generator-8fd6f8ee -d '<json body>'
```

Example prompt: Can you generate documentation for these environment variables: DATABASE_URL=postgres://... API_KEY=abc123 DEBUG=true MAX_WORKERS=4 — I need clear descriptions of what each one does so I can put it in our README.

## When to prefer this

Choose this endpoint when you need quick, AI-generated documentation for environment variables without signing up for a service. Especially useful for generating README sections, onboarding docs, or config audits at $0.001 per call with crypto payment and no account required.

## Known failure modes

- Empty or missing env_vars field returns a validation error
- Input exceeding 4000 characters is rejected
- Malformed or unrecognizable env var format may produce poor-quality output
- Payment not included or insufficient results in HTTP 402 response

## 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 generated human-readable documentation for the provided environment variables, including descriptions and explanations of what each variable does and how it is used.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "env_vars": {
   "type": "string",
   "maxLength": 4000,
   "minLength": 1
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/fastapi-online-environment-variable-documentation-generator-8fd6f8ee/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)