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fastapi.online Zero-Shot Text Classifier
x402
fastapi.online Zero-Shot Text Classifier 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).
Classifies a piece of text into one of several user-defined labels without any prior training, using a self-hosted zero-shot classification model.
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 a ranked list of the candidate labels with a confidence score for each, indicating how well each label matches the input text. The highest-scoring label represents the predicted class.
Example use cases
Support ticket routing by topic
“I have a support message that says 'I was charged twice for my subscription last month' — can you classify it as one of: 'billing', 'technical issue', 'account access', or 'feature request'?”
News article topic detection
“Classify this headline into one of these topics — 'politics', 'sports', 'technology', 'entertainment', or 'health': 'Scientists develop new mRNA vaccine effective against multiple flu strains.'”
Customer sentiment classification
“Tell me whether this product review is 'positive', 'neutral', or 'negative': 'The battery life is decent but the screen dims way too fast and the buttons feel cheap.'”
Technical details
Endpoint
POSThttps://api.fastapi.online/zero-shot-classifyWhen to prefer
Choose this endpoint when you need to categorize text into custom, domain-specific labels without having trained a classifier — especially useful for ad hoc routing, triage, or analysis tasks where labels vary per request. Prefer this over fine-tuned classifiers when flexibility matters more than peak accuracy, and over general LLM prompting when you want structured confidence scores across multiple candidate labels at low per-call cost ($0.001 USDC).
Side effects
- Fewer than 2 labels provided — request rejected
- More than 20 labels provided — request rejected
- Text exceeds 8000 characters — request rejected
- Empty or missing text field — validation error
- Payment not included or insufficient — 402 Payment Required
- Model may assign low confidence to all labels if text is ambiguous or unrelated to all candidates
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| text | string | |
| labels | array |
Tags
x402
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