# fastapi.online Antonym Suggest

> fastapi.online Antonym 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 antonyms for a given word, up to a specified count

## Facts

- Endpoint: POST https://api.fastapi.online/antonym-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-antonym-suggest-9105ff44
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_VrsC4J6Q5PJ0FQ4lBKmIF

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-antonym-suggest-9105ff44 -d '<json body>'
```

Example prompt: Can you suggest 5 antonyms for the word 'generous'?

## When to prefer this

Choose this endpoint when you need a lightweight, pay-per-call antonym lookup without requiring an account or subscription. Ideal for agents building vocabulary tools, writing assistants, or language learning apps that need quick opposite-word suggestions at very low cost ($0.0005 per call). Prefer alternatives if you need rich context, example sentences, or part-of-speech filtering alongside antonyms.

## Known failure modes

- Word not found or no antonyms available in the model's vocabulary — may return empty list or error
- Invalid input: word exceeds 100 characters or count exceeds 20 — returns validation error
- Network or service unavailability — returns 5xx error
- Payment not processed or insufficient funds — returns 402 Payment Required

## 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 antonym words (up to the requested count) for the input word, returned as structured data suitable for display or further processing in a writing or vocabulary application.

## 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-antonym-suggest-9105ff44/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)