# Callrack

> Callrack is a pay-per-use information infrastructure platform. Every capability below answers HTTP 402
> with x402 payment requirements; pay the advertised amount in USDC on Algorand and the response is yours.
> No accounts, no API keys, no subscriptions.

## Paid endpoints
- [Academic Search](https://api.callrack.xyz/v1/academic/search): Search scholarly literature via OpenAlex (falling back to Crossref) and return normalized works with titles, authors, publication years, DOIs, journals, citation counts, and open-access status. 0.01 USDC per call.
- [Academic Work Lookup](https://api.callrack.xyz/v1/academic/work): Retrieve a single scholarly work by DOI via OpenAlex (falling back to Crossref) and return its normalized title, authors, publication year, journal, citation count, and open-access status. 0.005 USDC per call.
- [News Search](https://api.callrack.xyz/v1/news/search): Search recent news coverage via GDELT and return normalized articles with titles, URLs, source domains, publish dates, languages, and countries. 0.01 USDC per call.
- [News Trends](https://api.callrack.xyz/v1/news/trends): Return normalized daily news-coverage volume for a topic, entity, or event via GDELT as a time series of dated volume points. 0.02 USDC per call.
- [Crypto Price](https://api.callrack.xyz/v1/crypto/price): Get current price and 24-hour change for one or more cryptocurrency assets in a specified quote currency via CoinGecko. 0.002 USDC per call.
- [Crypto Market Data](https://api.callrack.xyz/v1/crypto/market): Get market capitalization, rank, 24h volume, and circulating/total/max supply for one or more cryptocurrency assets via CoinGecko. 0.005 USDC per call.
- [FX Reference Rates](https://api.callrack.xyz/v1/fx/rates): Get current or historical foreign exchange reference rates for a base currency against one or more target currencies via Frankfurter (ECB data). 0.002 USDC per call.
- [Weather Forecast](https://api.callrack.xyz/v1/weather): Get current conditions and a multi-day daily forecast (temperature, humidity, wind, precipitation) for a coordinate via Open-Meteo. 0.003 USDC per call.
- [Geocode](https://api.callrack.xyz/v1/geocode): Forward geocode a place name to coordinates, or reverse geocode coordinates to a place, via Photon, returning normalized address components. 0.002 USDC per call.
- [Public Holidays](https://api.callrack.xyz/v1/holidays): Retrieve public holiday dates and names for a specified country and year via Nager.Date, including whether each holiday is observed nationwide. 0.002 USDC per call.
- [Knowledge Search](https://api.callrack.xyz/v1/knowledge/search): Search Wikidata for entities matching a free-text query and return normalized entity names, descriptions, and reference URLs. 0.005 USDC per call.
- [US Census Query](https://api.callrack.xyz/v1/government/census): Query a constrained subset of US Census Bureau statistical datasets and return the requested variables as normalized rows for the specified geography. 0.01 USDC per call.
- [Research Composition](https://api.callrack.xyz/v1/research): Aggregate information from selected Callrack research capabilities (academic, news, knowledge, and optionally government) and return structured research evidence with per-source status; deterministic composition, not an AI-generated answer. 0.05 USDC per call.
- [Verify](https://api.callrack.xyz/v1/verify): Verify a claim against existing Callrack capabilities (academic, news, knowledge) and return a deterministic verdict - supported, contradicted, mixed, or insufficient - with the underlying evidence. Uses explainable lexical term-overlap and negation-cue heuristics, never an LLM or semantic entailment. 0.05 USDC per call.
- [Evidence](https://api.callrack.xyz/v1/evidence): Return a machine-readable evidence pack for a query - real results from academic, news, and knowledge search with full source provenance and retrieval timestamps, never an AI-generated narrative answer. 0.05 USDC per call.
- [Compare](https://api.callrack.xyz/v1/compare): Compare information gathered from academic, news, and knowledge search for a query - distinct subjects, a flattened table of real attribute values, deduplicated sources, and any detected disagreements. Never fabricates a value a provider did not return. 0.10 USDC per call.

## Paying
- Protocol: x402 (v2), settled by https://facilitator.goplausible.xyz
- Network: Algorand TestNet · Asset: USDC (10458941)
- On HTTP 402, read the PAYMENT-REQUIRED response header (base64 JSON) for the exact, current price - never
  assume a price from this file; it can change.
- Clients: any x402 client - see https://facilitator.goplausible.xyz/guide

## Docs
- [OpenAPI](https://api.callrack.xyz/openapi.json)
- [Interactive docs](https://api.callrack.xyz/docs)
- [Operating instructions for agents](https://api.callrack.xyz/agents.md)