Feature
API Key Authentication
Simple key-based authentication for server-to-server calls.
78 providers
328 APIs
76 declared variants
Authentication via an issued API key or secret passed in a header or query parameter. The lowest-friction path to a first successful call, and still the default for most machine-to-machine integrations.
78 API providers on the APIs.io network offer api key authentication. The highest-rated are OpenAI, Iterable, UserGems, Healthie, Inworld AI.
Providers
Ranked by API Evangelist rating — Exemplar and Strong are expanded by default.
Exemplar 5 Complete, well-documented, and agent-ready
OpenAIOpenAI publishes a single unversioned REST API at https://api.openai.com/v1 covering text and reasoning (Re...IterableIterable is an AI customer engagement platform that powers unified cross-channel marketing experiences and ...UserGemsUserGems is a San Francisco-based sales intelligence platform that tracks champion job changes and surfaces...HealthieHealthie is a cloud, API-first EHR and practice management platform purpose-built for digital health startu...Inworld AIInworld AI is a real-time voice AI infrastructure provider. The Inworld platform delivers text-to-speech, s...
Strong 24 Solid coverage with minor gaps
PropelAuthPropelAuth is a B2B SaaS authentication and multi-tenant user management platform purpose-built for organiz...AshbyAshby is a modern all-in-one recruiting platform combining Applicant Tracking System (ATS), sourcing/CRM, i...SensibleSensible is a document-automation API platform that extracts structured data from PDFs, images, spreadsheet...Adafruit IOAdafruit IO is a cloud Internet of Things platform from Adafruit Industries built for makers, hobbyists, st...ThingSpeakThingSpeak is an IoT analytics platform from MathWorks that lets devices aggregate, visualize, and analyze ...ViamViam is a robotics and edge AI platform founded in 2020 by Eliot Horowitz (MongoDB co-founder and former CT...Apollo.ioApollo.io is a sales intelligence and go-to-market platform combining a database of 240M+ contacts and 30M+...EPA — U.S. Environmental Protection AgencyWeb services, data products, and open data spanning the U.S. Environmental Protection Agency. Programmatic ...RocketReachRocketReach is a Seattle-based B2B contact data and sales intelligence provider that maintains a database o...PaperspacePaperspace is a GPU cloud platform for AI, ML, and 3D rendering workloads, acquired by DigitalOcean in 2023...Leonardo.AILeonardo.AI is an Australian generative-AI company (acquired by Canva in July 2024) offering a Production A...IonQIonQ (NYSE IONQ) is a College Park, Maryland-based public trapped-ion quantum computing company. IonQ desig...AdaptAdapt (adapt.io) is a B2B lead intelligence and sales acceleration platform that provides a database of 250...MindeeMindee is a document parsing and intelligent document processing platform. Its REST API (api-v2.mindee.net)...AmplitudeAmplitude is a digital analytics platform that helps product teams understand user behavior, run experiment...SorsaSorsa Labs operates a real-time X (Twitter) data API providing developers access to tweets, profiles, searc...Track-PODTrack-POD is a cloud-based delivery management platform that combines route planning and optimization with ...TrueworkTruework operates a unified income and employment verification platform for mortgage lenders, credit unions...CalendarificWorldwide public holidays REST API covering 230+ countries. Calendarific provides national, local, religiou...ContinueContinue is the open-source AI code assistant for VS Code and JetBrains, distributed under Apache 2.0. The ...Arcade.devArcade.dev (formerly Arcade AI) is the MCP runtime for production AI agents — a platform that lets agents s...BandwidthBandwidth is a leading cloud-based communications platform providing voice, messaging, emergency calling, p...SmitherySmithery is an MCP server registry and hosting platform that lets developers discover, publish, and connect...US Census BureauThe U.S. Census Bureau is the federal statistical agency responsible for producing data about the American ...
Developing 32 Usable, with meaningful gaps to close
Amazon Managed GrafanaAmazon Managed Grafana is a fully managed service for open source Grafana developed in collaboration with G...FactorialFactorial is an all-in-one HR, payroll, time, talent, finance, and IT management platform headquartered in ...TensorTensor is the Solana-native NFT marketplace and trading protocol founded by Tensor HQ and now stewarded by ...UbiquitiUbiquiti Inc. (NYSE: UI) is an American networking technology company that designs and sells wireless a...VonageVonage (part of Ericsson) provides cloud communications APIs for voice, SMS, messaging, video, and verifica...KushkiKushki is an Ecuador-headquartered LatAm fintech operating as a regional non-banking acquirer for the Andea...VesselFinderVesselFinder is a maritime intelligence company operating a global AIS vessel-tracking network (terrestrial...API SnapAPI Snap is a developer utility platform that consolidates 13+ commonly needed REST APIs into a single, uni...PolyAPIPoly, built using cutting-edge AI and Kubernetes-native technology, accelerates development and simplifies ...PostHogPostHog is an open source product analytics platform that provides event tracking, session recording, featu...GreenhouseGreenhouse Software is an enterprise applicant tracking system (ATS) and end-to-end hiring platform spannin...openFDAopenFDA is the U.S. Food and Drug Administration's public data platform, providing Elasticsearch-backed RES...LambdaLambda gives your team instant access to the compute you need to build and deploy Artificial Intelligence. ...OpsGenieOpsGenie is an incident management and alerting platform, now part of Atlassian, that helps operations team...FastDOLFederal workplace enforcement records on 2.3M US employers across 16 federal agencies — OSHA, WHD, MSHA, EP...ShipStationShipStation is a leading shipping platform for ecommerce businesses providing APIs to integrate shipping wo...Aligned NewsAligned News is an AI-native intelligence and news platform that synthesizes AI-powered briefings from 63 c...StackOneStackOne is an AI-powered embedded integration platform as a service (iPaaS) designed to simplify and accel...TrackingMoreTrackingMore is a multi-carrier shipment tracking platform offering a unified REST API that integrates with...Australia PostAustralia Post is Australia's primary postal operator, offering a developer platform with REST APIs for e-c...LoopsLoops is a modern email platform purpose-built for software companies, combining product, marketing, and tr...Albato A Single No Code Platform For All AutomationsAlbato is a no-code automation platform enabling businesses to automate workflows by integrating 1,000+ app...Magic EdenMagic Eden is a multi-chain NFT marketplace offering REST and instruction-generation APIs for Solana, EVM c...Robin AIRobin AI is a London-headquartered legal intelligence platform founded in 2019 by former Clifford Chance di...Epidemic SoundEpidemic Sound is a Stockholm-based royalty-free music and sound effects licensing platform for video creat...NOAA — National Oceanic and Atmospheric AdministrationThe National Oceanic and Atmospheric Administration (NOAA) is the United States scientific and regulatory a...TomTomTomTom provides a comprehensive suite of location technology APIs and SDKs including maps, search, routing,...UnkeyUnkey is the developer platform for modern APIs, providing globally distributed API key management, rate li...NASA Open APIsNASA Open APIs is the National Aeronautics and Space Administration's unified, public developer portal expo...RedisRedis is an open source, in-memory data structure store used as a database, cache, message broker, and stre...TypesenseTypesense is a fast, typo-tolerant, open-source search engine designed for developer productivity. It provi...Agricultural Statistics ServiceThe National Agricultural Statistics Service (NASS) is an agency of the United States Department of Agricul...
Thin 14 Limited public surface area
Chicago Transit AuthorityThe Chicago Transit Authority (CTA) is the public transit operator for the City of Chicago and 35 surroundi...LangflowLangflow is an open-source low-code visual builder for AI agents, RAG pipelines, and LangChain-based workfl...LeverLever is a talent acquisition and applicant tracking platform built on the Opportunities data model. The Le...ElasticElastic is a software company that builds search-powered solutions for observability, security, and search ...SyndicaSyndica is a Solana-only infrastructure company building developer infrastructure for Web3. Its production ...trelloTrello is a web-based, kanban-style, list-making application that allows users to organize tasks, projects,...celestiaCelestia is the first production modular data availability blockchain. It separates consensus and data avai...honeycombBuild integrations and automate workflows with the Honeycomb API. Programmatically manage datasets, queries...io.netio.net is a decentralized GPU network for AI compute, built on Solana, that aggregates idle consumer and da...Lemon SqueezyLemon Squeezy is on a mission to make selling digital products easy-peasy. We know first-hand the challenge...GreenlyGreenly is a Paris-headquartered (with offices in London and New York) carbon accounting platform focused o...PaysafePaysafe is an integrated payment platform providing businesses with REST APIs for online payments, digital ...Amazon AppSyncAmazon AppSync creates serverless GraphQL and Pub/Sub APIs that simplify application development through a ...Canada PostCanada Post is the primary postal operator in Canada, offering a developer platform with REST and SOAP web ...
Emerging 3 Early or largely undocumented
HostfullyHostfully is a San Francisco-based short-term rental (STR) property management platform serving vacation re...API LeagueAPI League is a comprehensive API marketplace aggregating 60+ best-in-class APIs across categories includin...API-SportsAPI-Sports is a leading provider of real-time sports data and statistics APIs for businesses and developers...
What Providers Actually Declared
This feature is a canonical term. These are the free-text strings
providers wrote in their own apis.yml that map onto it.
10 requests/second per API key with burst to 20 req/s (token bucket)164 REST operations across 14 product modules — Applications, Candidates, Jobs, Openings, Job Postings, Interviews, Offers, Approvals, Surveys, Assessments, Custom Fields, Organization, Files, Reports, Webhooks, API Keys30-day-rotation API keys for programmatic MCP accessAPI Key ApplicationAPI Key AuthenticationAPI Key IssuanceAPI Key Self-ServiceAPI Key TiersAPI KeysAPI Keys Post Expiration WindowAPI Keys: create, verify, list, update, deleteAPI key + secret authAPI key authenticationAPI key authentication via Api-Key header; keys generated and rotated from Account SettingsAPI key authentication via `x-api-key` header or query parameterAPI key authentication via the userkey query parameterAPI key authentication via the x-api-key header; keys are scoped to an explicit endpoint list or marked masterAPI keys (Bearer)API keys per environmentAPI-key authentication via `Authorization: Basic` + `AuthorizationSource: API` (plus `AuthorizationShard` for sharded customers)Authentication via `x-tensor-api-key` header issued through dev.tensor.trade after Airtable applicationAuthentication: API key via Tracking-Api-Key headerAuto-generated OAuth UI modals for servers requiring API keys or user configurationBasic Access Authorization using Base64-encoded API keyBearer API key authentication; per-second concurrency limits scale by plan (1 → 10 → 25+)Bearer auth with API keys prefixed con_Bearer-token API key authentication with a GET /api-key test endpointBearer-token API keys, prefixed tw_sk_ (production) and tw_sk_test_ (sandbox)Concurrency, queue, and rate-limit controls scoped per API keyEnd-user API keys (personal and org-scoped) with validation, usage stats, and import of legacy keysFree API KeyFree API key with no published rate limit; one key per email; required for all data queriesFree and open weather, climate, ocean, fisheries, and space-weather APIs — no payment required and most endpoints require no API keyFree developer program registration; API keys issued per environment (sandbox and production)Funded by TIA staking and PayForBlobs gas fees; no central API key or commercial pricing tierGenieKey-based authentication (per integration)Granular per-endpoint API key permissions (Harvest API)Header-based authentication (email + apiKey) with 250 requests-per-minute rate limitJWT and API key/secret authJWT-based realtime authentication (separate Realtime-only API keys)
Showing 40 of 76 declared variants
Work with this as data
Every feature here is available over the APIs.io API and to AI agents over MCP. Features is not yet its own endpoint on the v1 API. Reach it through catalog search and the tag graph, or the MCP server.