YM.dat is a tiny browser-based tool for reading old Yahoo! Messengerdat chat archives. It detects your Yahoo! ID from the filename, lets you enter the contact ID, decodes the conversation locally, and exports a clean text transcript. No uploads, no install, no account. Just your old chats coming back to life.

I built YM.dat because I had been trying to read my old Yahoo! Messenger archives for years and never found a simple tool that worked for me. The few I came across were old, Windows-only, or not something I wanted to trust with personal chats. So I finally built the tool I wish existed. It runs completely in the browser. Your .dat files stay on your device. You enter the contact ID, drop the archive file, and YM.dat decodes the conversation into a readable format that you can export as text. This is a small tool, but it solves a very specific nostalgia problem. Somewhere inside those old files are usernames, bad spellings, late-night jokes, random game references, and tiny pieces of a web that no longer exists. Would love feedback, especially from anyone else who still has Yahoo! Messenger archives lying around.

This is such a specific and nostalgic tool! Did you build this to recover old personal data, or was there a technical curiosity about the .dat file structure?

@rivra_dev Primarily to recover personal data. I had loads of chat archives lying around since late 2000s and I was never able to find a tool that reliably does this. :)

This is such a specific and nostalgic tool! Did you build this to recover old personal data, or was there a technical curiosity about the .dat file structure?

@rivra_dev Primarily to recover personal data. I had loads of chat archives lying around since late 2000s and I was never able to find a tool that reliably does this. :)

YM.dat

Read old Yahoo! Messenger .dat archives locally

Read old Yahoo! Messenger .dat archives locally