# fastapi.online — Complaint Response Generator

> fastapi.online — Complaint Response Generator is a paid API for AI agents from api.fastapi.online, paid per call via x402, $0.0015/call, status unknown (last checked 2026-09-14).

Generates a professional written response to a customer complaint using self-hosted AI inference

## Facts

- Endpoint: POST https://api.fastapi.online/complaint-response-generate
- Price: $0.0015/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-complaint-response-generator-8f3e1bd1
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_ZkFCJYKdXcG763m6pulI0

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-complaint-response-generator-8f3e1bd1 -d '<json body>'
```

Example prompt: Draft a professional response to this customer complaint: 'I ordered a laptop three weeks ago and it still hasn't arrived. Your support team has been completely unhelpful and I want a refund immediately.'

## When to prefer this

Choose this endpoint when you need a quick, pay-per-call, no-signup solution for generating professional complaint responses. It is particularly useful for automating customer service workflows, handling high volumes of complaint replies, or building agent pipelines that need to respond to negative feedback at scale. At $0.0015 per call it is cost-effective for bulk usage and crypto-native workflows via x402.

## Known failure modes

- Empty or missing complaint field returns a validation error
- Complaint text exceeding 4000 characters is rejected
- Model inference failures may return a 500 error
- Payment not completed or insufficient USDC balance results in 402 Payment Required
- Rate limits or server overload may cause timeouts

## 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 professionally written text response to the submitted complaint, suitable for direct use in customer service, email replies, or public review responses. The response is generated by a self-hosted AI model and typically includes acknowledgment of the complaint, an empathetic tone, and a constructive reply.

## Request schema (JSON Schema)

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

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/fastapi-online-complaint-response-generator-8f3e1bd1/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)