Find Mastodon Accounts in Twitter Followings

This tool allows you to connect your Twitter Account and check if any people you follow have specified their Mastodon Handle in their profile or a pinned Tweet.
You will then be able to select accounts from a list and export a CSV file you can then import into Mastodon.

The tool is heavily inspired by already existing Tools like Fedifinder and Debirdify. The algorithm to detect Mastodon Handles in profiles is copied from Fedifinder. This tool is mostly a proof-of-concept and cannot match up to the features and usability of these other tools. The amount of false positives, for example, is much larger.

The objective for this tool was to provide a comparable application, that does not depend on any server-side logic/code and allows you to keep full control over your data, without ever sharing your data or Twitter access-token with a server that is not under your control. Because the Twitter API does not allow direct connections from browsers (Cross Origin Resource Sharing is disabled) you need a CORS proxy that allows the browser to make those requests (the proxy can see all the data!).

There are publically available CORS proxies, but their availability and trustworthiness cannot be guaranteed. To keep full control over your data you can launch your own CORS proxy on your machine or disable CORS-checks in your browser, though I cannot and do not personally vouch for any of these suggestions, which are merely some unchecked Google results:

• There are browser extensions available, that allow to temporarily disable the CORS-checks.
  For example, the "Allow CORS: Access-Control-Allow-Origin" extension that is available for Chrome and Firefox. If you use these, you can provide https://api.twitter.com as the proxy address, because no proxy is needed. Make sure to disable these extensions in your browser after you are done using the tool.
• If you have Python, you can use corsa:

  corsa --allow-proxy https://api.twitter.com --allow-origin https://mapeper.github.io

  The proxy address is then: http://127.0.0.1:8888/proxy/https://api.twitter.com
• If you have Node.js, you can probably also use local-cors-proxy, cors-anywhere, corsproxy, or any other CORS proxy.
• I prepared a PowerShell/C# Script, that should not require any additional dependencies on Windows 7 and beyond. You will need to provide https://mapeper.github.io as an allowed Origin and https://api.twitter.com/ as a target URI:

  powershell -executionpolicy bypass -Command .\cors-proxy.ps1 -targetUris "https://api.twitter.com" -allowedOrigins "https://mapeper.github.io"

The irony of a tool, that does not require trusting a server with your data, but instead requires trust to install and execute a script/program on your system, isn't lost on me.