I built an app that turns Reddit threads into a podcast, with a different on-device AI voice per commenter. It's live.

Hey IH 👋

Solo founder here (Pixel Labs). A couple of weeks ago I posted that I was building ThreadCast. It's live on Google Play now, so here's the launch and the one decision I'm still chewing on.

The itch: I read a lot of Reddit, but always on a tiny screen at the worst times, on a commute, at the gym, doing dishes. I kept wanting to just listen. Every text-to-speech app I tried read the whole thing in one flat robot voice. A 40-comment thread turned into an unlistenable monotone wall. You lose who's saying what almost immediately.

So I built ThreadCast. It takes a thread (post + top comments) and reads it aloud like a podcast, and the part I'm proudest of: every commenter gets their own voice. Drop into a thread, hit play, and it actually sounds like a conversation instead of one person droning. That one detail changed how listenable a long thread is more than anything else I tried.

The technical bet that made it hard (and, I think, worth it):

The AI neural voices run 100% on the device. No cloud, no account, nothing leaves your phone. Most read-aloud tools ship your text to a server to synthesize; ThreadCast deliberately doesn't. The upside beyond privacy is that once you've downloaded the voices and a thread, it all works offline, so you can listen on a plane with no signal. Getting good neural voices to run locally on a phone was the bulk of the engineering, but it's the whole thesis, so I wasn't going to compromise on it.

What it actually does today:

· Multi-voice playback, up to 11 on-device AI voices, a different one per author.

· Comment control: it reads the post + top comments, and you choose which comments and how deep, so you're not stuck listening to 200 replies.

· Queue + local save: line up posts, and threads (post and comments) get saved locally for offline listening later.

· Sleep mode: 10 ambient sounds + a fade-out timer, because I mostly use this in bed.

· Lock-screen, Bluetooth, and media controls, no account needed.

· Full TalkBack support: an app that reads Reddit aloud should be genuinely great for people who need it read aloud, so accessibility wasn't an afterthought. Every control is labeled and swipe actions are exposed as screen-reader actions.

· MP3 export (Premium): save any thread as a shareable audio file and listen in any podcast app.

Free vs Premium: free gets you your phone's system voices, browsing, the queue, comment control, sleep mode, and lock-screen controls, basically the whole listening loop. Premium is the on-device AI voices + MP3 export. No ads, no tracking, no VC, just me trying to build something people pay a fair price for.

There's also a free Chrome extension for desktop, and it's not a lite version, it's the same core: four on-device voice engines, the multi-voice narration, comment selection, a docked side panel, and sleep mode. The only things still coming to the extension are MP3 export and reading stuff beyond Reddit (PDFs, articles, your own text). iOS is later.

The thing I keep going back and forth on, and where I'd genuinely love this community's take:

1. How do you price a local-first app? My whole moat is that the AI runs on-device, which means no per-use server cost, but also no usage meter to anchor a subscription to. One-time vs subscription for something with basically zero marginal cost has me stuck.

2. The per-commenter-voices thing: does that actually sound like a real feature to you, or like a gimmick? It's the part I bet the product on, and I'm curious whether it lands the same way for people who aren't me.

Play Store: https://play.google.com/store/apps/details?id=app.threadcast

Chrome extension: https://chromewebstore.google.com/detail/threadcast/dhbcjkjfhebbjffojpcmfoffhchijpkn

Site: https://threadcast.app

Happy to get into any of the on-device/offline details if that's interesting. Thanks for reading.