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fastapi.online Tone Adjust
x402
fastapi.online Tone Adjust is a paid API for AI agents from api.fastapi.online, paid per call via x402, $0.001/call, status unknown (last checked 2026-09-15).
Rewrites a given text in a specified tone (e.g. formal, friendly, persuasive) using a self-hosted AI model, paid per call.
Price / call$0.001
Success—
StatusUnknown
How this service works
Chat, embeddings, OCR, speech-to-text, image editing, image understanding (captioning/Q&A), text-to-speech, translation, writing tools, classification tools, developer tools, local utilities, format/checksum validators, encoding & crypto utilities, date/time calculators, geo/coordinate math, math & 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 the original text rewritten in the requested tone. The output is a string of AI-generated prose that preserves the core meaning and information of the input while adjusting stylistic and emotional qualities to match the specified tone.
Example use cases
Professionalizing a casual email draft
“I wrote this to my client but it sounds too casual — can you make it sound more formal and professional? Here's the text: 'Hey! So yeah we finished that thing you asked about, let us know what you think ok?'”
Softening a harsh rejection message
“This rejection email I drafted sounds way too blunt — can you rewrite it in a more empathetic and gentle tone? Text: 'We are not moving forward with your application. You were not a good fit.'”
Making marketing copy more persuasive
“Can you rewrite this product description in a persuasive tone to make it more compelling for buyers? Here's the text: 'This is a water bottle. It holds 32 oz and has a lid.'”
Technical details
Endpoint
POSThttps://api.fastapi.online/tone-adjustWhen to prefer
Choose this endpoint when you need a lightweight, per-call, no-signup tone transformation for text of up to 8000 characters and want to pay with crypto (USDC). It is ideal for agents that need tone adjustment without committing to a subscription, or when integrating into an x402 payment workflow. Prefer alternatives like OpenAI or Anthropic APIs if you need a guaranteed specific model, fine-grained control over generation parameters, or higher throughput.
Side effects
- Empty or missing 'text' field returns a validation error
- Missing or blank 'tone' field returns a validation error
- Text exceeding 8000 characters is rejected
- Ambiguous or unsupported tone strings may produce inconsistent results
- Payment failure (402) if USDC payment is not provided or insufficient
- Model may occasionally produce output that partially drifts from the requested tone
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| text | string | |
| tone | string |
Tags
x402
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