Mock sample for your project: FishEye API

The reliable, secure, and simple IP geolocation 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.
Change Management:
The major version of the API endpoint can be determined / specified in the URL localhost:8080/v1/connections/create
Minor version bumps will be invisible to the end user. The user cannot specify minor versions in requests.
All backwards incompatible changes will happen in major version bumps. We will not make backwards incompatible changes in minor version bumps. Examples of non-breaking changes (includes but not limited to...):
Adding fields to request or response bodies.
Adding new HTTP endpoints.

Introduction
Api2Pdf is a powerful PDF generation API with no rate limits or file size constraints. Api2Pdf runs on AWS Lambda, a serverless architecture powered by Amazon to scale to millions of requests while being up to 90% cheaper than alternatives. Supports wkhtmltopdf, Headless Chrome, LibreOffice, and PDF Merge. You can also generate barcodes with ZXING (Zebra Crossing).
SDKs & Client Libraries
We've made a number of open source libraries available for the API
Python: https://github.com/api2pdf/api2pdf.python
.NET: https://github.com/api2pdf/api2pdf.dotnet
Nodejs: https://github.com/api2pdf/api2pdf.node
PHP: https://github.com/Api2Pdf/api2pdf.php
Ruby: (Coming soon)
Authorization
Create an account at portal.api2pdf.com to get an API key.
Authorize your API calls
GET requests, include apikey=YOUR-API-KEY as a query string parameter
POST requests, add Authorization to your header.
For more advanced usage and settings, see the API specification below.

Appwrite backend as a service cuts up to 70% of the time and costs required for building a modern application. We abstract and simplify common development tasks behind a REST APIs, to help you develop your app in a fast and secure way. For full API documentation and tutorials go to https://appwrite.io/docs

Domain API (WHOIS, Check, Batch)

Wikipedia for Web APIs. Repository of API specs in OpenAPI 3.0 format.
Warning: If you want to be notified about changes in advance please join our Slack channel.
Client sample: [Demo] [Repo]

This API provides validation information for email addresses to aid in deliverability. Syntax, existence of mail servers, and other tests are run to ensure delivery. Additional demographics are provided for the email address as well, including identifying generic, vulgar, education, government, or other entity type email addresses.

This is a REST API reference for the Keycloak Admin

This API provides a similarity key used to match with other similar full name data when data fields are parsed into first name and last name components, including for purposes of deduplication, fuzzy matching, or merging of datasets. A much higher match rate will be achieved by matching on the similarity key rather than the data itself. This API is for full name data where first and last name are in separate fields. Use the Full Name Similarity Key API for first and last name data that are in the same field.

Converter and validator for Swagger 2.0 to OpenAPI 3.0.x definitions

This API provides the two-letter state abbreviation (or the province abbreviation for Canada) for the purposes of standardizing state name data, improving query results, analytics, and data merging.