# fastapi.online Synonym Suggest

> fastapi.online Synonym Suggest is a paid API for AI agents from api.fastapi.online, paid per call via x402, $0.0005/call, status unknown (last checked 2026-09-14).

Returns a list of synonyms for a given word, up to a specified count

## Facts

- Endpoint: POST https://api.fastapi.online/synonym-suggest
- Price: $0.0005/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-synonym-suggest-e1c978d6
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_HToazfogT4d1DlWeCqElg

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-synonym-suggest-e1c978d6 -d '<json body>'
```

Example prompt: Can you suggest 8 synonyms for the word 'melancholy' so I can vary my writing?

## When to prefer this

Choose this endpoint when you need quick, pay-per-call synonym suggestions without signup, especially in agent workflows where no Merriam-Webster or Thesaurus.com API key is available. Best for lightweight vocabulary enrichment tasks where cost per call ($0.0005 USDC) is preferable to subscription-based alternatives. Ideal for anonymous, one-off lookups paid with crypto.

## Known failure modes

- Word not recognized or too obscure — may return empty synonym list
- Count exceeds maximum of 20 — request rejected with validation error
- Empty or blank word input — returns 400 validation error
- Word with length over 100 characters — rejected by schema
- Network or model inference failure — returns 5xx error

## 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

A list of synonym words (up to the requested count) for the input word, returned as structured data from a self-hosted NLP model.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "word": {
   "type": "string",
   "maxLength": 100,
   "minLength": 1
  },
  "count": {
   "type": "integer",
   "maximum": 20,
   "minimum": 1
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/fastapi-online-synonym-suggest-e1c978d6/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)