# API Atlas

> A concise, static, source-backed catalog of APIs. Mutable facts show official sources and verification dates.

## Machine-readable indexes
- [Catalog JSON](https://getbeta.app/api-atlas/api/catalog.json): Normalized provider catalog
- [Changes JSON](https://getbeta.app/api-atlas/api/changes.json): Meaningful catalog and policy changes

## Provider profiles
- [Alpaca](https://getbeta.app/api-atlas/apis/alpaca/): US stock market data with explicit IEX or consolidated SIP feed selection, historical REST queries, and live WebSocket streams.
- [Alpha Vantage](https://getbeta.app/api-atlas/apis/alpha-vantage/): A function-based market-data API for equities, options, forex, crypto, commodities, economic indicators, fundamentals, and technical indicators.
- [BOK ECOS](https://getbeta.app/api-atlas/apis/bok-ecos/): The Bank of Korea's official economic-statistics API for Korean monetary, financial, price, national-account, and related time series.
- [Claude API](https://getbeta.app/api-atlas/apis/anthropic/): Anthropic's API for Claude messages, tool use, token counting, batches, files, and related platform capabilities.
- [Cloudflare API](https://getbeta.app/api-atlas/apis/cloudflare/): A broad control-plane API for Cloudflare accounts, zones, DNS, Workers, Pages, storage, and security products.
- [CoinGecko API](https://getbeta.app/api-atlas/apis/coingecko/): Crypto asset prices, metadata, markets, exchanges, NFTs, and onchain datasets.
- [Currencylayer](https://getbeta.app/api-atlas/apis/currencylayer/): A hosted foreign-exchange API for live, historical, conversion, timeframe, and currency-change queries.
- [DeepSeek Search & Fetch](https://getbeta.app/api-atlas/apis/deepseek/): Dedicated web retrieval APIs for agent workflows, with tool-specific authentication, usage accounting and limits separate from model inference.
- [EODHD](https://getbeta.app/api-atlas/apis/eodhd/): A broad financial-data API covering end-of-day prices, fundamentals, corporate actions, intraday data, news, and more.
- [Financial Modeling Prep API](https://getbeta.app/api-atlas/apis/financial-modeling-prep/): Comprehensive financial data: real-time quotes, 30 years of financial statements, ratios, insider transactions, and analyst estimates. Strong for fundamental analysis.
- [Finnhub API](https://getbeta.app/api-atlas/apis/finnhub/): Real-time and historical market data for stocks, forex, and crypto. Generous free tier for US stocks; premium endpoints (e.g. historical candles) require paid plans.
- [FRED API](https://getbeta.app/api-atlas/apis/fred/): Official programmatic access to FRED economic series, observations, releases, sources, and metadata.
- [FSC Basic Fund Product Information](https://getbeta.app/api-atlas/apis/fsc-data-go-kr/): An official Korean public API for fund names, standard codes, operators, categories, types, and reference dates.
- [FSS DART API](https://getbeta.app/api-atlas/apis/fss-dart/): Korea's official corporate filing system (like US EDGAR) — financial statements, disclosures, and company info for KOSPI/KOSDAQ listed companies.
- [Gemini API](https://getbeta.app/api-atlas/apis/gemini/): Google's developer API for Gemini models, multimodal generation, embeddings, files, tools, and live interactions.
- [GitHub REST API](https://getbeta.app/api-atlas/apis/github-rest/): GitHub's official REST surface for repositories, collaboration, Actions, Git data, and account resources.
- [KRX API](https://getbeta.app/api-atlas/apis/krx/): Official market data from Korea Exchange — KOSPI, KOSDAQ, ETF prices, and trading statistics.
- [Mapbox APIs](https://getbeta.app/api-atlas/apis/mapbox/): Mapping platform APIs for maps, tiles, styles, geocoding, navigation, routing, and spatial analysis.
- [Massive](https://getbeta.app/api-atlas/apis/massive/): A market-data platform for stocks, options, futures, indices, forex, crypto, economic, and alternative datasets.
- [Neon API](https://getbeta.app/api-atlas/apis/neon/): Serverless PostgreSQL platform with branching, autoscaling, and a management REST API.
- [Notion API](https://getbeta.app/api-atlas/apis/notion/): A workspace content API for pages, blocks, data sources, comments, users, search, and webhooks.
- [Open-Meteo API](https://getbeta.app/api-atlas/apis/open-meteo/): Weather forecast, historical, marine, air-quality, and geocoding APIs with an accessible public tier.
- [OpenAI API](https://getbeta.app/api-atlas/apis/openai/): A model platform for text, multimodal input, structured outputs, tools, embeddings, image, audio, and agent-oriented workflows.
- [Oracle Cloud Infrastructure API](https://getbeta.app/api-atlas/apis/oci/): REST APIs for provisioning and managing Oracle Cloud Infrastructure resources including compute instances, networking, and storage.
- [Paddle Billing API](https://getbeta.app/api-atlas/apis/paddle/): Merchant-of-record billing APIs for products, prices, customers, transactions, and subscriptions.
- [Render API](https://getbeta.app/api-atlas/apis/render/): Cloud platform API for managing web services, databases, background workers, and deployments.
- [SEC EDGAR APIs](https://getbeta.app/api-atlas/apis/sec-edgar/): Official JSON and bulk-data access to company filing submissions and XBRL facts.
- [SEIBRO](https://getbeta.app/api-atlas/apis/seibro/): Korea Securities Depository securities information portal, with a research case on dividend list completeness and count reconciliation.
- [Slack Web API](https://getbeta.app/api-atlas/apis/slack/): Method-oriented APIs for Slack messages, conversations, users, files, views, and workspace integrations.
- [Stripe API](https://getbeta.app/api-atlas/apis/stripe/): A mature payments and billing API covering checkout, payment intents, subscriptions, invoicing, and platforms.
- [Supabase Data APIs](https://getbeta.app/api-atlas/apis/supabase/): Auto-generated REST and GraphQL data APIs backed by a project's Postgres schema, alongside Auth, Storage, and Realtime.
- [Treasury Fiscal Data API](https://getbeta.app/api-atlas/apis/treasury-fiscal-data/): Official U.S. Treasury fiscal datasets with filtering, sorting, field selection, and pagination.
- [Twelve Data API](https://getbeta.app/api-atlas/apis/twelve-data/): Market data for stocks, forex, crypto, ETFs, and indices via REST and WebSocket. 100+ technical indicators computed server-side. Generous free tier for prototyping.
- [Twilio Messaging API](https://getbeta.app/api-atlas/apis/twilio/): Programmable messaging APIs for SMS, MMS, WhatsApp, media, and delivery callbacks.
- [World Bank Indicators API](https://getbeta.app/api-atlas/apis/world-bank/): Public access to World Bank development indicators and their country, source, and topic metadata.
- [yfinance](https://getbeta.app/api-atlas/apis/yfinance/): An open-source Python library that retrieves market data through Yahoo Finance's publicly available interfaces.

## Comparisons
- [EODHD vs Massive](https://getbeta.app/api-atlas/compare/eodhd-vs-massive/): Start with EODHD when global EOD coverage and a wide catalog from one vendor dominate; start with Massive when U.S. market structure, streaming, and bulk delivery are central. In either case, validate commercial display and redistribution rights separately from API access.
- [EODHD vs Alpha Vantage](https://getbeta.app/api-atlas/compare/eodhd-vs-alpha-vantage/): Alpha Vantage is the faster low-volume prototype; EODHD is usually the more natural starting point for a scheduled ingestion system that needs wider market coverage, corporate actions, and multiple datasets.
- [OpenAI API vs Anthropic Claude API](https://getbeta.app/api-atlas/compare/openai-vs-anthropic/): There is no durable winner by brand or benchmark headline. Run a versioned evaluation on your own inputs; choose the smallest model that meets quality, tool reliability, latency, governance, and total-cost targets.
- [OpenAI API vs Google Gemini API](https://getbeta.app/api-atlas/compare/openai-vs-gemini/): Choose through workload testing and ecosystem fit. Gemini is especially natural beside Google Cloud and AI Studio workflows; OpenAI offers its own broad model-and-tools platform. Treat model IDs, previews, prices, and quotas as dated inputs—not architecture constants.
- [Massive vs Alpha Vantage](https://getbeta.app/api-atlas/compare/massive-vs-alpha-vantage/): Use Alpha Vantage to validate a small, low-frequency idea quickly. Use Massive when the product needs a deliberate path toward U.S. market depth, streaming, quotes/trades, or bulk history—subject to the correct business license.
- [Anthropic Claude API vs Google Gemini API](https://getbeta.app/api-atlas/compare/anthropic-vs-gemini/): Choose by workload and ecosystem: Claude's direct API rewards explicit versioning and organization-level governance, while Gemini leans on per-project quotas, a free tier for prototyping, and Google-native multimodal workflows — validate model IDs and prices on your own inputs before committing.
- [Stripe API vs Paddle Billing API](https://getbeta.app/api-atlas/compare/stripe-vs-paddle/): Use Stripe when you own the payments stack and need broad payment-method and platform coverage; use Paddle when you want a merchant of record to absorb global sales-tax and compliance handling for SaaS subscriptions.
- [FRED API vs World Bank Indicators API](https://getbeta.app/api-atlas/compare/fred-vs-world-bank/): Use FRED for U.S. macro series with release calendars and revision metadata; use the World Bank API for cross-country development indicators — both are free, but their coverage, formats, and revision semantics differ.
- [EODHD vs yfinance](https://getbeta.app/api-atlas/compare/eodhd-vs-yfinance/): Prototype in a notebook with yfinance; build the product on EODHD (or another contracted feed) once you need stable entitlements, corporate actions, and someone to hold accountable for the data.
- [Treasury Fiscal Data API vs FRED API](https://getbeta.app/api-atlas/compare/treasury-fiscal-data-vs-fred/): Reach for the Treasury Fiscal Data API when the question is what the U.S. federal government collected, spent, or owes; reach for FRED when the question is the state of the economy — both are free, but their coverage, metadata, and discovery models differ.
- [FSC Fund Product API vs BOK ECOS](https://getbeta.app/api-atlas/compare/fsc-data-go-kr-vs-bok-ecos/): Use the FSC fund-product service for official Korean fund identifiers and standard codes; use BOK ECOS for Korean macroeconomic time series — both are free public portals, but one is an identifier lookup and the other is a statistics engine.
- [yfinance vs Alpha Vantage](https://getbeta.app/api-atlas/compare/yfinance-vs-alpha-vantage/): Prototype in a notebook with yfinance; reach for Alpha Vantage when you need a hosted API with a real key, documented quotas, and premium throughput — both are free to start, but only one is a service.
- [Massive vs yfinance](https://getbeta.app/api-atlas/compare/massive-vs-yfinance/): Prototype with yfinance; move to Massive (or another contracted feed) when you need WebSocket streams, deeper history, bulk flat files, and a vendor behind the data.
- [Neon vs Supabase](https://getbeta.app/api-atlas/compare/neon-vs-supabase/): Use Neon when you want pure serverless Postgres with branching and already have your own backend; use Supabase when you want Auth, Storage, Realtime, and auto-generated REST APIs out of the box.

## Guides
- [How to choose a stock market data API](https://getbeta.app/api-atlas/guides/choose-stock-market-data-api/): Turn a vague data wish list into a tested decision on coverage, adjustments, latency, rights, and total operating cost.
- [How to choose an LLM API](https://getbeta.app/api-atlas/guides/choose-llm-api/): Select a model platform with a reproducible evaluation instead of chasing a leaderboard or a single token price.
- [How to handle API keys safely](https://getbeta.app/api-atlas/guides/api-key-safety/): Keep credentials out of source, clients, logs, and accidental blast radii with a practical key lifecycle.
- [How to implement REST pagination](https://getbeta.app/api-atlas/guides/rest-pagination-patterns/): Build one resilient iterator across page numbers, offsets, cursors, and next-link APIs without losing or duplicating records.
- [How to design API retries and backoff](https://getbeta.app/api-atlas/guides/retry-and-backoff/): Retry only recoverable failures, honor server signals, and prevent a transient outage from becoming a retry storm.
- [How to verify API rate limits](https://getbeta.app/api-atlas/guides/verify-api-rate-limits/): Record quota facts without turning a stale pricing table or old blog post into production truth.
- [How to consume an OpenAPI specification](https://getbeta.app/api-atlas/guides/consume-openapi-specification/): Use an official API specification for discovery and validation without generating an unmaintainable wall of code or thin pages.
- [Gemini API thought_signature 400 error: preserve parallel function-call history](https://getbeta.app/api-atlas/guides/gemini-thought-signature-parallel-tool-calls/): A reported Gemini 3 Flash Preview 400 came from splitting parallel function calls into separate model history entries. Keep the original response grouping and signature position.
- [Massive (Polygon) API missing minute aggregate bars: check limit and trade conditions](https://getbeta.app/api-atlas/guides/massive-polygon-missing-aggregate-bars/): Missing Massive minute bars can reflect a base-aggregate limit or no eligible trades. Finish pagination, then inspect trades and conditions for the exact minute.
- [EODHD missing dividend data: handle delayed updates and cache refreshes](https://getbeta.app/api-atlas/guides/eodhd-dividend-delay-cache-refresh/): A successful dividend request can still return an incomplete observation. Reusing that observation for seven days can hide a later update; scheduled collection needs a fresh observation and explicit coverage limits.
- [SEIBRO dividend API pagination: reconcile count and collected rows](https://getbeta.app/api-atlas/guides/seibro-dividend-pagination-count-mismatch/): Receiving the last nonempty page is not enough to prove a dividend window is complete. Pin the count, validate page coverage and duplicates, and refuse an unstable window before confirming financial facts.
- [ECOS exchange rate API: prevent selecting a non-USD currency](https://getbeta.app/api-atlas/guides/ecos-usd-currency-identity-validation/): Valid ECOS JSON can still be interpreted as the wrong currency. Select and validate the USD item explicitly; never turn the first row into a compatibility fallback when the expected currency is absent.
- [yfinance Adj Close missing: check auto_adjust and MultiIndex](https://getbeta.app/api-atlas/guides/yfinance-adj-close-auto-adjust-multiindex/): A missing Adj Close and unexpected tuple columns can both follow yf.download defaults. Set adjustment and column shape explicitly before reading a price series.
- [EODHD + SEIBRO Korean dividend dates missing: route collection by listing market](https://getbeta.app/api-atlas/guides/eodhd-seibro-korean-dividend-source-selection/): EODHD support identified a Korean .KO date-field coverage limit: ex-date and amount are supplied, while declaration, record and payment dates are not. Route KR dividends to confirmed SEIBRO events; keep EODHD for the US dividend path and avoid cross-source field grafting.
- [LLM API retries and fallback: avoid applying timeout budgets twice](https://getbeta.app/api-atlas/guides/llm-retry-fallback-shared-timeout-budget/): A fallback chain must spend one request budget. Giving every retry and provider a fresh timeout can multiply latency, especially when application retries are combined with SDK retries.
- [LLM structured output: preserve response_format through fallback](https://getbeta.app/api-atlas/guides/llm-structured-output-fallback-response-format/): An adapter that accepts response_format but drops it can silently turn a structured request into free text. Fallback must preserve the same output contract or explicitly refuse the request.
- [Alpaca API recent SIP data error: choose delayed SIP or explicit IEX](https://getbeta.app/api-atlas/guides/alpaca-api-recent-sip-data-error-iex/): Alpaca Basic can reject recent SIP requests. Choose a historical SIP window outside the restricted interval, or explicitly accept IEX-only coverage before changing feeds.
- [OpenAI Responses API commentary parsing errors: select final structured output](https://getbeta.app/api-atlas/guides/openai-responses-parse-commentary-final-answer/): A completed response can contain commentary before valid final JSON. Older Python SDK parsing can reject the commentary or return it as the structured result; the phase-aware fix preserves commentary while selecting eligible final output.
- [Anthropic Claude API mixed-tool missing results and 400 errors: resume the unfinished tool turn](https://getbeta.app/api-atlas/guides/anthropic-mixed-tools-missing-result-400/): A missing server result in a mixed Claude tool response can be deferred, not lost. Continue with every client result, preserve tool definitions and correlate later results by ID before treating the turn as complete.
- [yfinance repair price unit mismatch: check pence, pounds and fix versions](https://getbeta.app/api-atlas/guides/yfinance-repair-pence-pound-currency-unit-mismatch/): Repair can expose a quotation-unit mismatch before FX valuation. Separate the documented restoration fix from unmerged follow-up work, and normalize only with verified history currency.
- [OpenAI Responses API lost instructions: resend policy with previous_response_id](https://getbeta.app/api-atlas/guides/openai-responses-previous-response-id-instructions/): Chaining response context does not reapply the preceding top-level instructions. Put stable policy in every request and verify the actual payload before blaming the model or switching plans.
- [Alpaca get_all_assets TXSE validation error: check the SDK enum and release](https://getbeta.app/api-atlas/guides/alpaca-py-txse-assetexchange-validation-error/): An unfamiliar exchange value can reject an entire typed asset list. Preserve the raw catalog, expose unsupported values and verify the installed release instead of treating a closed issue as a shipped fix.
- [DeepSeek Search 401 with a chat proxy: separate tool credentials and endpoints](https://getbeta.app/api-atlas/guides/deepseek-search-401-proxy-credential-endpoint/): A working chat route does not validate the credential for a separate search service. Bind each tool to its intended origin and credential issuer before retrying or enabling automatic search.

## Policies
- [Source and crawler policy](https://getbeta.app/api-atlas/sources/)
- [About API Atlas](https://getbeta.app/api-atlas/about/)

Official vendor documentation remains authoritative. API Atlas does not mirror full vendor docs.