Other APIs (Unofficial Web/App API Clients): open-source projects that exist because someone reverse engineered a closed product, sorted by GitHub stars.
RSS feed generator that scrapes hundreds of sites and apps, many via unofficial APIs
Python data interface for Baidu, Google, Toutiao and Weibo indexes and macro data
Python package (formerly IMDbPY) that retrieves IMDb data from its web pages
Router client for the Xunlei Kuainiao broadband acceleration service
Unofficial ESPN endpoint documentation and reference code
Sends messages to members of Congress by reverse engineering their web contact forms
Unofficial reference for the NHL API endpoints
Unified API proxy for Pixiv, Bilibili, NetEase Cloud Music and other sites
Unified CLI with JSON output for Xiaohongshu, Douyin, TikTok, Bilibili, Weibo, Xianyu, Taobao and X
Unofficial Node.js API for HLTV.org Counter-Strike matches, results, teams and players
Post and live-start notifier for Bilibili, Weibo, Xiaohongshu and Douyin
Unofficial Formula 1 schedule, results and live timing data in Home Assistant
Unofficial speedtest.net command-line client in C++
Unofficial documentation of the Synology Photos API
Unofficial API client for the Korean Dong-hang Lottery site
Unofficial client for Premier League stats, fixtures and results
Unofficial command-line client for dict.cc
Unofficial Python API for the ThisPersonDoesNotExist website
Unofficial cross-platform SamacSys component library loader
Unofficial OpenTable API
Go client for Ultimate-Guitar's mobile API
Unofficial Android client for the Huishenghuo 798 campus water dispenser service
Tool that discovers undocumented APIs from the AWS Console
Unofficial Rust CLI for the speed.cloudflare.com speed test backend
Documentation of ProPresenter's undocumented remote control protocol
Unofficial client for the Kleenex/Scottex pollen radar data in Home Assistant
Catalog of undocumented Amazon S3 APIs and third-party extensions
GasBuddy fuel prices via the unofficial GasBuddy GraphQL API
Python library for AWS services driven by undocumented APIs not in boto3
Write-up and code for the reverse-engineered Casper private API
Self-hosted SofaScore data platform using the private SofaScore API
Unofficial API wrapper for the Seedr.cc cloud torrent service
Unofficial API wrapper for Qwant search
Synology unofficial API CLI and library
Norwegian Posten mail-delivery days via the unofficial Posten API
Dynamic DNS client for Hover using its unofficial API
Reverse-engineered WhatPulse client protocol
Download Windows Spotlight lock screen images via the Content Delivery Manager API
Unofficial API and CLI for archive.today
Unofficial API for Downdetector outage reports
Python library for Synack's undocumented API endpoints
Unofficial Pikud HaOref red alert monitor publishing alerts to MQTT
Vodafone DE contract usage (minutes, SMS, data) via the unofficial MeinVodafone API
Unofficial asynchronous Python wrapper for HLTV.org Counter-Strike data
Unofficial wrapper for the F1 Fantasy API
Unofficial API for Compass, the UK Scouts membership system
Reverse-engineered API client for Simple Mining OS
Unofficial Weathercloud personal weather station client built from a reverse-engineered API
Rust wrapper for the undocumented Akinator API
Unofficial Ruby wrapper for the FotMob API
Python wrapper for the undocumented FotMob football API
Unofficial Akinator API wrapper
Unofficial library for Rotten Tomatoes movie and TV data
Documentation for hidden FedEx Ship Manager® API
Unofficial async Python client and API notes for the Librus Synergia school e-gradebook
Exports Xiaomi Mi Fitness health data to SQLite and CSV
LegoSharp is an unofficial C# library for interacting with Lego's web APIs.
API wrapper for the Magic Seaweed (MSW) surf-forecast app
Reverse-engineered documentation of CHMI weather radar image providers
API Wrapper for NobodySurf
Documentation of the undocumented API behind Municode city ordinance websites