# API Finder

> Describe a capability your agent needs. Receive a verified, structured shortlist of APIs that provide it: official documentation, current pricing, authentication, SDKs, rate limits, free tier, restrictions — each backed by a first-party quote, or marked inferred/unknown.

Operator: Active Life Hub LLC
Base URL: https://apifinder.online
Current mode: live
Payment network: Base mainnet (eip155:8453), USDC via x402 v2

## Discovery
- [OpenAPI schema](https://apifinder.online/openapi.json)
- [API instructions](https://apifinder.online/docs)
- [Pricing JSON](https://apifinder.online/api/v1/pricing)
- [Health (configuration only; no database)](https://apifinder.online/api/v1/health)
- [Terms](https://apifinder.online/terms) · [Privacy](https://apifinder.online/privacy)

## Prices
Quick: 0.33 USDC. Standard: 0.51 USDC. Deep: 0.64 USDC.
Pricing version api-finder-cost-plus-2026-09-28-v1. Multiplier 3x. Minimum 0.10 USDC. The price is fixed before payment: the calibrated variable cost of one research attempt for the tier (search, extraction, model, compute, database, storage, settlement), multiplied by the configured markup (3×, i.e. cost + 200%). Actual usage is recorded per request; there is no usage surcharge or automatic price true-up.
POST /api/v1/quote with your request body for a free price check.

## Buy a research request
1. Generate and persist a random Idempotency-Key (16-128 letters/digits/_/-). It is also your private result access key.
2. POST /api/v1/find with that key and JSON {"capability":"Find an API that can translate PDF files","max_results":5}. text/plain is also accepted. Max 16 KiB. You do not need to know provider names.
3. Receive HTTP 402 with x402 v2 requirements in PAYMENT-REQUIRED (base64) and in the body.
4. Check asset, destination, network and price. Use an x402 client with a spending limit to sign an EIP-3009 USDC authorization. Resend the identical body and key with PAYMENT-SIGNATURE.
5. Payment settles through Coinbase Developer Platform before research. 200 returns apis[] ranked, each with provider_name, api_name, website, documentation_url, pricing_url, capability_summary, features, endpoints, attributes{authentication,sdks,pricing,free_tier,rate_limits,geographic_restrictions,commercial_use,data_residency,availability,latency}, pricing_freshness, requirement_checks, ranking_basis, known_limitations, evidence[] and confidence; plus excluded_candidates[] with reasons.
6. For 202 or later retrieval: GET /api/v1/requests/{id} with Authorization: Bearer <original Idempotency-Key>.

## Optional input fields
description, geography, jurisdiction, programming_language, auth_methods[], max_price{amount,currency,unit}, latency, free_tier_required, commercial_use_required, data_residency, must_have[], nice_to_have[], exclude[], max_results (1-10), tier (quick|standard|deep), preferred_output_language, search_languages[], max_price_usdc.
Mandatory (need first-party evidence): must_have, auth_methods, free_tier_required, commercial_use_required, data_residency, constraints stated in capability. Screening (exclude only if contradicted): geography, jurisdiction, max_price, latency. Soft: programming_language, nice_to_have.

## Evidence statuses
verified = value + source_url + verbatim quote + retrieved_at from the provider's own domain; prices, limits, endpoints, auth and SDKs must appear literally in the quote.
inferred = labelled conclusion in note; never carries a value (no inferred prices, limits or auth).
unknown = not stated in retrieved documentation; value null.
Pricing is never estimated. Unverified pricing says "contact provider / check pricing page".

## Ranking
Candidates are kept only when capability relevance and every mandatory requirement are verified by a quote from the provider’s own pages. Survivors are ordered by: (1) number of optional requirements verified, (2) whether current pricing is verified from an official page, (3) whether a free tier or trial is verified, (4) number of verified attributes (auth, SDKs, limits, availability, etc.), (5) evidence-based confidence, then name. No hidden or model-generated score is used.

## Languages and geography
Write the request in any language. preferred_output_language (e.g. "ru", "ja", "pt-BR") sets the language of explanations; otherwise the detected request language is used, with English fallback for ambiguous input (language.note). Geography is independent of language: local markets are searched in their own languages (search_plan). Provider names, endpoints, prices and quotes stay verbatim; evidence[].source_language labels them; quote_translation and name_alias are convenience only.

## Spending ceiling
Send max_price_usdc to refuse (HTTP 422, nothing charged) if the tier price exceeds it. Also enforce a spending limit in your x402 client.

## Retries
On connection errors resend the same body and key with the same PAYMENT-SIGNATURE or with Authorization: Bearer <key>. Up to two free retries of failed paid research. Never start a new payment after settlement_unknown; keep the request ID. Zero-match completed research is charged. No automatic refunds.

## Demo
Only in mode demo: fictional PDF-translation providers; send PAYMENT-SIGNATURE: demo:<Idempotency-Key>. Live mode rejects this.

Do not submit secrets or personal data. Live research sends request content to search and model providers. Results describe public documentation at retrieval time and are not guarantees.