# fastapi.online JSON to CSV Converter

> fastapi.online JSON to CSV Converter is a paid API for AI agents from api.fastapi.online, paid per call via x402, $0.0005/call, status unknown (last checked 2026-09-15).

Converts an array of JSON objects into a CSV-formatted string, with optional column ordering and custom delimiter.

## Facts

- Endpoint: POST https://api.fastapi.online/json-to-csv
- Price: $0.0005/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/fastapi-online-json-to-csv-converter-32587e34
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_NXzEaGFby656U9zm4RdqB

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-json-to-csv-converter-32587e34 -d '<json body>'
```

Example prompt: Convert this JSON array to CSV with columns in the order name, age, email, and use a semicolon as the delimiter: [{"name":"Alice","age":30,"email":"alice@example.com"},{"name":"Bob","age":25,"email":"bob@example.com"}]

## When to prefer this

Use this endpoint when you need a quick, serverless, pay-per-call JSON-to-CSV conversion without setting up a local library or managing dependencies. Ideal for agents that receive JSON data and need to export it as a spreadsheet-compatible format on the fly. At $0.0005 per call it is cost-effective for occasional conversions. Prefer a local library (e.g. Python csv module) for high-volume or sensitive data that shouldn't leave your environment.

## Known failure modes

- Missing or empty rows array returns an error or empty CSV
- Invalid delimiter (more than one character) is rejected
- Rows with inconsistent keys may produce empty cells for missing fields
- Malformed JSON in the request body returns a 400/422 validation error
- Payment not included or insufficient USDC triggers a 402 Payment Required 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 a CSV-formatted string where each JSON object becomes a row, columns are ordered as specified (or derived from keys), and fields are separated by the chosen delimiter (default comma). The first line is the header row with column names.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "rows": {
   "type": "array",
   "items": {
    "type": "object"
   }
  },
  "columns": {
   "type": "array",
   "items": {
    "type": "string"
   }
  },
  "delimiter": {
   "type": "string",
   "maxLength": 1
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/fastapi-online-json-to-csv-converter-32587e34/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)