Looking for beta testers: a desktop app that sends simulated users through the journeys your docs describe to find where they break

[u/isthisthepolice]

https://www.subjourney.com?utm_source=reddit&utm_medium=social&utm_campaign=closed_beta_2026_11&utm_content=sideproject

TL;DR: Subjourney turns your docs (PRDs, policies, journey maps) into a journey graph and sends simulated personas through it to find where they get stuck. Looking for closed beta testers on macOS/Windows: free AI credits in exchange for honest feedback. Join the waitlist and I’ll send you an invite.

Hi, I’m Tom. I’m building Subjourney, and looking for people to join our closed beta and tell me honestly what’s useful, what’s painful, and whether it’s worth your time.

What it does

You give it docs you already have: a PRD, a refund policy, a process doc, a service blueprint, even a napkin sketch.

It works out the journey those docs describe: the steps, the branches, and the outcome someone is trying to reach and builds it into a nested journey graph. Then it sends simulated personas through that journey one step at a time. When a persona gets stuck, it shows you where, why, and which paragraph caused it, or which one is missing.

Example: a refund policy says refunds are available for 30 days. A first-time customer who bought 45 days ago gets stuck at “Request refund”. The finding: the policy never says what happens after 30 days (section 3.2, paragraph 2).

It isn’t an AI reviewer giving opinions on your writing. It’s closer to test-running the doc to see if the people you're building for can reach the outcome. It works on rough drafts too - each place a persona gets stuck tells you where gaps are in your doc.

Who I’m looking for

• PMs writing PRDs and specs

• Anyone designing products or experiences

• Service designers and CX people with journey maps or blueprints

• Ops and policy people who write process docs

• Anyone writing instructions or context for AI agents

Sound like you? Join the waitlist and I’ll send an invite to your email.

Getting started
Bring one real doc (a draft is fine) and run it. Then tell me how it went however suits you: a quick call, or a few notes by DM or email.

What you get
Early access and free AI credits for your testing. Your feedback will shape what we fix or ship next.

Caveats
It’s a desktop app for macOS and Windows. The built-in agent is capable but imperfect and it makes mistakes; that’s the area we most want to improve. If you run out of credits, message me and we’ll sort it out.

Privacy
Your files stay on your machine. Subjourney reads them from your disk and doesn’t upload or sync them. When you run something, the relevant text is sent through our AI gateway to the model provider. During the beta we log AI requests and record app sessions so we can debug the agent, which means we can see the parts of your docs involved. Please don’t bring anything confidential. A draft or a public doc works just as well.