APIs · shortlist
Best free APIs
Which free APIs are actually worth integrating depends on how well they are documented and whether they need a key before you can make a single request. This shortlist is drawn from the live catalogue and ordered by documentation completeness.
How this list was ordered. There is no reliable popularity signal in the source registries, so entries are ranked by how completely the record is documented — a substantial description plus a documentation, repository or base URL — and then alphabetically. 1,257 apis in this scope clear the content bar; the top 24 are shown. A place here is not an endorsement or a paid slot.
Shortlisted entries
- 01
Account API
This API is used for the classic integration. If you are just starting your implementation, refer to our new integration guide instead. The Account API provides endpoints for managing account-related entities on your platform. These related entities include account holders, accounts, bank accounts, shareholders, and verification-related documents. The management operations include actions such as creation, retrieval, updating, and deletion of them. For more information, refer to our documentation. ## Authentication Your Adyen contact will provide your API credential and an API key. To connect to the API, add an X-API-Key header with the API key as the value, for example: curl -H "Content-Type: application/json" \ -H "X-API-Key: YOURAPIKEY" \ ... Alternatively, you can use the username and…
Payment auth: API Key
api.apis.guru/v2/specs/adyen.com/AccountService/6/openapi.json ↗
- 02
Accounting API
Welcome to the Accounting API. You can use this API to access all Accounting API endpoints. ## Base URL The base URL for all API requests is https://unify.apideck.com We also provide a Mock API that can be used for testing purposes: https://mock-api.apideck.com ## Headers Custom headers that are expected as part of the request. Note that RFC7230 states header names are case insensitive. | Name | Type | Required | Description | | --------------------- | ------- | -------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------- | | x-apideck-consumer-id | String | Yes | The id of the customer stored inside Apideck Vault. This can be a user id, account id, device id or whatever entity tha…
Developer Tools auth: API Key
api.apis.guru/v2/specs/apideck.com/accounting/9.3.0/openapi.json ↗
- 03
Adyen Balance Control API
The Balance Control API lets you transfer funds between merchant accounts that belong to the same legal entity and are under the same company account. ## Authentication To connect to the Balance Control API, you must authenticate your requests with an API key or basic auth username and password. To learn how you can generate these, see API credentials.Here is an example of authenticating a request with an API key: curl -H "X-API-Key: YourAPIkey" \ -H "Content-Type: application/json" \ ... Note that when going live, you need to generate API credentials to access the live endpoints. ## Versioning The Balance Control API supports versioning using a version suffix in the endpoint URL. This suffix has the following format: "vXX", where XX is the version number. For example: https://pal-test.ad…
Payment auth: API Key
api.apis.guru/v2/specs/adyen.com/BalanceControlService/1/openapi.json ↗
- 04
Adyen BinLookup API
The BIN Lookup API provides endpoints for retrieving information, such as cost estimates, and 3D Secure supported version based on a given BIN. ## Authentication You need an API credential to authenticate to the API. If using an API key, add an X-API-Key header with the API key as the value, for example: curl -H "Content-Type: application/json" \ -H "X-API-Key: YOURAPIKEY" \ ... Alternatively, you can use the username and password to connect to the API using basic authentication, for example: curl -U "ws@Company.YOURCOMPANYACCOUNT":"YOURBASICAUTHENTICATIONPASSWORD" \ -H "Content-Type: application/json" \ ... ## Versioning The BinLookup API supports versioning using a version suffix in the endpoint URL. This suffix has the following format: "vXX", where XX is the version number. For exampl…
Payment auth: API Key
api.apis.guru/v2/specs/adyen.com/BinLookupService/54/openapi.json ↗
- 05
Adyen Checkout API
Adyen Checkout API provides a simple and flexible way to initiate and authorise online payments. You can use the same integration for payments made with cards (including 3D Secure), mobile wallets, and local payment methods (for example, iDEAL and Sofort). This API reference provides information on available endpoints and how to interact with them. To learn more about the API, visit online payments documentation. ## Authentication Each request to Checkout API must be signed with an API key. For this, get your API key from your Customer Area, and set this key to the X-API-Key header value, for example: curl -H "Content-Type: application/json" \ -H "X-API-Key: YOURAPIKEY" \ ... ## Versioning Checkout API supports versioning using a version suffix in the endpoint URL. This suffix has the fol…
Payment auth: API Key
api.apis.guru/v2/specs/adyen.com/CheckoutService/70/openapi.json ↗
- 06
Adyen Data Protection API
Adyen Data Protection API provides a way for you to process Subject Erasure Requests as mandated in GDPR. Use our API to submit a request to delete shopper's data, including payment details and other related information (for example, delivery address or shopper email).## Authentication Each request to the Data Protection API must be signed with an API key. Get your API Key from your Customer Area, as described in How to get the API key. Then set this key to the X-API-Key header value, for example: curl -H "Content-Type: application/json" \ -H "X-API-Key: YourAPIkey" \ ... Note that when going live, you need to generate a new API Key to access the live endpoints. ## Versioning Data Protection Service API supports versioning using a version suffix in the endpoint URL. This suffix has the fo…
Payment auth: API Key
api.apis.guru/v2/specs/adyen.com/DataProtectionService/1/openapi.json ↗
- 07
Adyen Payment API
A set of API endpoints that allow you to initiate, settle, and modify payments on the Adyen payments platform. You can use the API to accept card payments (including One-Click and 3D Secure), bank transfers, ewallets, and many other payment methods. To learn more about the API, visit Classic integration. ## Authentication You need an API credential to authenticate to the API. If using an API key, add an X-API-Key header with the API key as the value, for example: curl -H "Content-Type: application/json" \ -H "X-API-Key: YOURAPIKEY" \ ... Alternatively, you can use the username and password to connect to the API using basic authentication, for example: curl -U "ws@Company.YOURCOMPANYACCOUNT":"YOURBASICAUTHENTICATIONPASSWORD" \ -H "Content-Type: application/json" \ ... ## Versioning Payment…
Payment auth: API Key
api.apis.guru/v2/specs/adyen.com/PaymentService/68/openapi.json ↗
- 08
Adyen Payout API
A set of API endpoints that allow you to store payout details, confirm, or decline a payout. For more information, refer to Online payouts. ## Authentication To use the Payout API, you need to have two API credentials: one for storing payout details and submitting payouts, and another one for confirming or declining payouts. If you don't have the required API credentials, contact our Support Team. Both of these API credentials must be authenticated with basic authentication.The following example shows how to authenticate your request when submitting a payout: curl -U "storePayout@Company.YOURCOMPANYACCOUNT":"YOURBASICAUTHENTICATIONPASSWORD" \ -H "Content-Type: application/json" \ ... ## Versioning Payments API supports versioning using a version suffix in the endpoint URL. This suffix has…
Payment auth: unknown
api.apis.guru/v2/specs/adyen.com/PayoutService/68/openapi.json ↗
- 09
Adyen Recurring API
The Recurring APIs allow you to manage and remove your tokens or saved payment details. Tokens should be created with validation during a payment request. For more information, refer to our Tokenization documentation. ## Authentication You need an API credential to authenticate to the API. If using an API key, add an X-API-Key header with the API key as the value, for example: curl -H "Content-Type: application/json" \ -H "X-API-Key: YOURAPIKEY" \ ... Alternatively, you can use the username and password to connect to the API using basic authentication, for example: curl -U "ws@Company.YOURCOMPANYACCOUNT":"YOURBASICAUTHENTICATIONPASSWORD" \ -H "Content-Type: application/json" \ ... ## Versioning Recurring API supports versioning using a version suffix in the endpoint URL. This suffix has t…
Payment auth: API Key
api.apis.guru/v2/specs/adyen.com/RecurringService/68/openapi.json ↗
- 10
Airbyte Configuration API
Airbyte Configuration API https://airbyte.io. This API is a collection of HTTP RPC-style methods. While it is not a REST API, those familiar with REST should find the conventions of this API recognizable. Here are some conventions that this API follows: All endpoints are http POST methods. All endpoints accept data via application/json request bodies. The API does not accept any data via query params. The naming convention for endpoints is: localhost:8000/{VERSION}/{METHODFAMILY}/{METHODNAME} e.g. localhost:8000/v1/connections/create. For all update methods, the whole object must be passed in, even the fields that did not change. Authentication (OSS): When authenticating to the Configuration API, you must use Basic Authentication by setting the Authentication Header to Basic and base64 en…
Developer Tools auth: unknown
api.apis.guru/v2/specs/airbyte.local/config/1.0.0/openapi.json ↗
- 11
Apacta
API for a tool to craftsmen used to register working hours, material usage and quality assurance. # Endpoint The endpoint https://app.apacta.com/api/v1 should be used to communicate with the API. API access is only allowed with SSL encrypted connection (https). # Authentication URL query authentication with an API key is used, so appending ?apikey={apikey} to the URL where {apikey} is found within Apacta settings is used for authentication # Pagination If the endpoint returns a pagination object it means the endpoint supports pagination - currently it's only possible to change pages with ?page={pagenumber} but implementing custom page sizes are on the road map. # Search/filter Is experimental but implemented in some cases - see the individual endpoints' docs for further explanation. # Ord…
Time Management auth: API Key
- 12
Apicurio Registry API [v2]
Apicurio Registry is a datastore for standard event schemas and API designs. Apicurio Registry enables developers to manage and share the structure of their data using a REST interface. For example, client applications can dynamically push or pull the latest updates to or from the registry without needing to redeploy. Apicurio Registry also enables developers to create rules that govern how registry content can evolve over time. For example, this includes rules for content validation and version compatibility. The Apicurio Registry REST API enables client applications to manage the artifacts in the registry. This API provides create, read, update, and delete operations for schema and API artifacts, rules, versions, and metadata. The supported artifact types include: - Apache Avro schema -…
Developer Tools auth: unknown
api.apis.guru/v2/specs/apicurio.local/registry/2.4.x/openapi.json ↗
- 13
AppVeyor REST API
AppVeyor is a hosted continuous integration service which runs on Microsoft Windows. The AppVeyor REST API provides a RESTful way to interact with the AppVeyor service. This includes managing projects, builds, deployments, and the teams that build them. Additional help and discussion of the AppVeyor REST API is available at http://help.appveyor.com/discussions This Swagger definition is an unofficial description of the AppVeyor REST API maintained at https://github.com/kevinoid/appveyor-swagger Please report any issues or suggestions for this Swagger definition at https://github.com/kevinoid/appveyor-swagger/issues/new #### API Conventions Fields which are missing from update operations (PUT requests) are typically reset to their default values. So although most fields are not technically…
Developer Tools auth: unknown
- 14
ART19 Content API Documentation
The ART19 Content API conforms to the JSON:API specification. API requests MUST use the HTTP Accept header: Accept: application/vnd.api+json API requests MUST be authenticated using the HTTP Authorization header: Authorization: Token token="your-token", credential="your-credential" ## General Notes Some query parameters use unencoded [ and ] characters simply for readability. Defaults, examples, and possible values are additionally rendered in double quotes for readability. In practice, query parameters should not have quotes around the values (e.g., foo=bar is valid, not foo="bar"), and both query parameter keys and values must be percent-encoded, per the requirements in RFC 3986 § 3.4. ## Rate Limiting In order to provide a fair distribution of available resources, all API calls are sub…
Media auth: Token
- 15
Asynchronous Speech-To-Text API Documentation
Rev.ai provides quality speech-text recognition via a RESTful API. All public methods and objects are documented here for developer reference. For a real-time speech to text solution, use Rev.ai's Streaming API. # Base Endpoint The base url for this version of the API is > https://api.rev.ai/speechtotext/v1 All endpoints described in this documentation are relative to this base url. # Quick Start Follow the getting started checklist ## Get your Access Token You can generate your access token on the settings page of your account. This access token only needs to be generated once and never expires. You can re-generate your token, however this will invalidate the previous token. ## Submit a File To submit an audio file for transcription to Rev.ai: curl -X POST "https://api.rev.ai/speechtotex…
Text auth: Token
- 16
ATS API
Welcome to the ATS API. You can use this API to access all ATS API endpoints. ## Base URL The base URL for all API requests is https://unify.apideck.com We also provide a Mock API that can be used for testing purposes: https://mock-api.apideck.com ## Headers Custom headers that are expected as part of the request. Note that RFC7230 states header names are case insensitive. | Name | Type | Required | Description | | --------------------- | ------- | -------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------- | | x-apideck-consumer-id | String | Yes | The id of the customer stored inside Apideck Vault. This can be a user id, account id, device id or whatever entity that can have int…
Developer Tools auth: API Key
- 17
AWS Compute Optimizer
Compute Optimizer is a service that analyzes the configuration and utilization metrics of your Amazon Web Services compute resources, such as Amazon EC2 instances, Amazon EC2 Auto Scaling groups, Lambda functions, Amazon EBS volumes, and Amazon ECS services on Fargate. It reports whether your resources are optimal, and generates optimization recommendations to reduce the cost and improve the performance of your workloads. Compute Optimizer also provides recent utilization metric data, in addition to projected utilization metric data for the recommendations, which you can use to evaluate which recommendation provides the best price-performance trade-off. The analysis of your usage patterns can help you decide when to move or resize your running resources, and still meet your performance an…
Cloud auth: unknown
api.apis.guru/v2/specs/amazonaws.com/compute-optimizer/2019-11-01/openapi.json ↗
- 18
AWS IoT Core Device Advisor
Amazon Web Services IoT Core Device Advisor is a cloud-based, fully managed test capability for validating IoT devices during device software development. Device Advisor provides pre-built tests that you can use to validate IoT devices for reliable and secure connectivity with Amazon Web Services IoT Core before deploying devices to production. By using Device Advisor, you can confirm that your devices can connect to Amazon Web Services IoT Core, follow security best practices and, if applicable, receive software updates from IoT Device Management. You can also download signed qualification reports to submit to the Amazon Web Services Partner Network to get your device qualified for the Amazon Web Services Partner Device Catalog without the need to send your device in and wait for it to b…
Cloud auth: unknown
api.apis.guru/v2/specs/amazonaws.com/iotdeviceadvisor/2020-09-18/openapi.json ↗
- 19
AWS Transfer Family
Transfer Family is a fully managed service that enables the transfer of files over the File Transfer Protocol (FTP), File Transfer Protocol over SSL (FTPS), or Secure Shell (SSH) File Transfer Protocol (SFTP) directly into and out of Amazon Simple Storage Service (Amazon S3) or Amazon EFS. Additionally, you can use Applicability Statement 2 (AS2) to transfer files into and out of Amazon S3. Amazon Web Services helps you seamlessly migrate your file transfer workflows to Transfer Family by integrating with existing authentication systems, and providing DNS routing with Amazon Route 53 so nothing changes for your customers and partners, or their applications. With your data in Amazon S3, you can use it with Amazon Web Services for processing, analytics, machine learning, and archiving. Gett…
Cloud auth: unknown
api.apis.guru/v2/specs/amazonaws.com/transfer/2018-11-05/openapi.json ↗
- 20
BC Laws
BC Laws is an electronic library providing free public access to the laws of British Columbia. BC Laws is hosted by the Queen's Printer of British Columbia and published in partnership with the Ministry of Justice and the Law Clerk of the Legislative Assembly.BC Laws contains a comprehensive collection of BC legislation and related materials. It is available on the internet in two forms:First: The library is available as a web site in which users can browse and search the laws of British Columbia.Second: The library is available as a portal to legislation in raw XML data format, accessible via the BC Laws API2. This direct access to raw data is intended to enable third parties to build or add their own custom applications based on the structure of the data and all the associated search fu…
Open Data auth: unknown
api.apis.guru/v2/specs/bclaws.ca/bclaws/1.0.0/openapi.json ↗
- 21
Benefits Intake
The Benefits Intake API allows authorized third-party systems used by Veteran Service Organizations (VSOs), agencies, and Veterans to digitally submit VA benefits claim documents directly to the Veterans Benefits Administration's (VBA) claims intake process. This API handles documents related to the following benefit claim types: Compensation Pension/Survivors Benefits Education Fiduciary Insurance Veteran Readiness & Employment (VRE) Board of Veteran Appeals (BVA) This API also provides submission status updates until documents are successfully established for VBA claim processing, eliminating the need for users to switch between systems to manually check whether documents have been successfully uploaded. ## Background This API provides a secure, efficient, and tracked alternative to mai…
Open Data auth: API Key
- 22
Billbee API
Documentation of the Billbee REST API to connect a Billbee account to external aplications. ## Endpoint The Billbee API endpoint base url is https://api.billbee.io/api/v1 ## Activation You have to enable the API in the settings of your Billbee account. In addition you need a Billbee API Key identifying the application you develop. To get an API key, send a mail to support@billbee.io and send us a short note about what you are building. ## Authorization & security Because you can access private data with the Billbee API, every request has to be sent over https and must Contain a valid API Key identifying the application/developer. It has to be sent as the HTTP header X-Billbee-Api-Key Contain a valid user login with billbee username and api password in form of a basic auth HTTP header ## T…
Ecommerce auth: API Key
- 23
Catalog API
> Check the new Catalog onboarding guide. We created this guide to improve the onboarding experience for developers at VTEX. It assembles all documentation on our Developer Portal about Catalog and is organized by focusing on the developer's journey. Methods for collecting product/SKU catalog data, categories, brands and other information. All content that comes between {{}} keys must be replaced with the correct data before performing the request. ## Index - Product - Here you can consult, create, or update a Product. For more information, check this article. - Product Specification - You can consult, create, or update additional information of a Product. For more information, check this article. - SKU - Here you can consult, create, or update an SKU. For more information, check this art…
Development auth: Token
api.apis.guru/v2/specs/vtex.local/Catalog-API/1.0/openapi.json ↗
- 24
Catalog API - Seller Portal
With the Catalog API for Seller Portal, you will be able to create, edit and consult products and their variations, brands, and categories. > This API is part of the Seller Portal Catalog. This functionality is in the Beta stage and can be discontinued at any moment at VTEX's discretion. VTEX will not be responsible for any instabilities caused by its use or discontinuity. If you have any questions, please contact our Support Center. ## Index ### Product GET Get Product by ID PUT Update Product GET Get Product Description by Product ID PUT Update Product Description by Product ID GET Get Product by external ID, SKU ID, SKU external ID or slug POST Create Product ### SKU GET Search for SKU GET Get List of SKUs ### Brand GET Get List of Brands POST Create a Brand GET Get Brand by ID PUT Upd…
Development auth: unknown
api.apis.guru/v2/specs/vtex.local/Catalog-API-Seller-Portal/1.0.0/openapi.json ↗
Snapshot 2026-09-18. Fields shown are what the source registry stated, not a live probe — check the linked documentation before integrating. See the methodology.