Promptleak
Find the secret in the prompt
Problem
Secrets end up in prompts. An engineer pastes a config to debug, an agent reads an env file and includes it in context, a log captures the lot. The key is now in a third party's logs, and rotating it requires knowing it happened, which nobody does.
Why now
Agents read local files as a matter of course now, which means the path from a project's .env to a third party's logs is one careless tool call. That path did not exist before 2025, and it is now the default shape of a coding session.
Solution
It sits on the way out. Prompts and tool outputs are scanned for credential shapes before they leave the machine, and a match is blocked and reported rather than logged. The engineer finds out at the moment it would have leaked.
Who it is for
Any team whose agents can read the filesystem, which is now most of them. The person who feels it is the engineer who realised that the path from a project's env file to a third party's logs is a single careless tool call. They cannot rotate what they do not know leaked, and that is the part that keeps them up: the failure is silent by design.
What you could earn from Promptleak
Say you build Promptleak and charge your own customers $25 a month, the price the score suggests. The numbers below are the revenue that would come from them. This is money you earn, never a fee you pay UpgradIQ, and we never take a cut. It is arithmetic off the price, not a promise the customers arrive on their own.
See what Promptleak produces
It sits on the way out. Prompts and tool outputs are scanned for credential shapes before they leave the machine, and a match is blocked and reported rather than logged. The engineer finds out at the moment it would have leaked.
Your build kit for Promptleak
Start the build and the kit opens two steps in, then drip-feeds the rest one phase at a time. Every phase is a copy-paste prompt for your agent with its own verification before the next unlocks, so Promptleak moves from an empty folder to a running MVP without you ever holding the whole plan in your head.
Progress saves across every device, and the workspace always reopens on the exact step you left, so a build that runs over several weeks survives them instead of dying in a browser tab you eventually close.
How you actually build it
Connect your coding agent once. It pulls the current phase straight from your kit over MCP: the exact prompt, the outcome to aim for, and the check to run before it moves on. You review and ship, it does the typing.
No copy-paste juggling, no thread to lose. The kit stays the single source of truth, and your agent works through it one phase at a time, verifying its own work at each step before the next phase is unlocked.
Take the context file, free
This is the AGENTS.md that keeps your coding agent on scope for the entire build: what Promptleak is, who it is for, the stack, the non-goals, and the rules it must follow. Copy it into your project now, no account needed, and your agent is briefed before you write a line.
# Promptleak Find the secret in the prompt ## What this is It sits on the way out. Prompts and tool outputs are scanned for credential shapes before they leave the machine, and a match is blocked and reported rather than logged. The engineer finds out at the moment it would have leaked. ## The problem it solves Secrets end up in prompts. An engineer pastes a config to debug, an agent reads an env file and includes it in context, a log captures the lot. The key is now in a third party's logs, and rotating it requires knowing it happened, which nobody does. ## Who it is for Any team whose agents can read the filesystem, which is now most of them. The person who feels it is the engineer who realised that the path from a project's env file to a third party's logs is a single careless tool call. They cannot rotate what they do not know leaked, and that is the part that keeps them up: the failure is silent by design. ## Stack Next.js + Postgres ## Non-goals Do not build features outside the core job above. This product exists to do one thing well. Every extra feature is a reason it does not ship. ## Rules for the agent - Build one phase at a time. Do not run ahead into later phases. - Validate input at every boundary where data enters. - Never put a permission or plan check in client code. - Ask before adding a dependency that a few lines would cover. - If something is ambiguous, say so rather than inventing a requirement. --- Context file from UpgradIQ · idea promptleak · prompts kit-v4
Then start free to get the ten-phase kit and run the first prompt.
The path to a running MVP
Foundation
Scaffold the stack, then wire the data model and sign-in. It is the skeleton Promptleak stands on, and it goes up in an evening rather than a lost week of config.
The product
Build the core feature end to end, then wire how it charges. This is where Promptleak finally turns into something that a stranger will actually pay you for.
Ship it
Test and harden, deploy it live, then open the launch-day toolkit that lands the first ten users who prove it.
Is Promptleak for you?
- You want revenue reasonably soon, not a science project
- You can give it evenings and a couple of weekends
- You can reach Teams shipping agents
- You are not ready to talk to a first real customer
- You want it fully passive, with zero maintenance
- You expect it to find its own customers without you
The 3 sections that decide whether you should actually build it, plus the full kit, are one click away.
3 more sections decide whether you build Promptleak
You have the case and the plan. Pro opens how it makes money, the one risk that kills it, and the build notes, plus the 10-phase kit that takes Promptleak to a running MVP, on this idea and all 200.
How it makes money
Main risk
Build notes
What is free here, and what Pro unlocks
Frequently asked
Is Promptleak actually validated?
It scored UIQ 83 with a GO verdict, weighed across eight sub-scores on the same rubric as every idea. GO means 75 and above, so demand and buildability were judged, not guessed.
What stack does it use?
Promptleak is built on Next.js + Postgres, chosen because a coding agent can carry most of it. You are not fighting infrastructure, you are shipping the feature that matters.
How long to a running MVP?
The kit is ten phases, drip-fed one at a time so you always know the single next step. An evening and a weekend for the lighter builds, a few focused weeks for the deeper ones.
What does the $25 a month mean?
It is the price the model suggests Promptleak could charge its own customers, not a fee to us. It is here so the money question is answered before you build, not after.
Which agent do I need?
Any capable coding agent: Claude Code, Cursor, Lovable, or Bolt. Every phase is a copy-paste prompt with its own check, so the agent does the typing and you keep the judgement.
What is free versus Pro?
The whole case above is free: the problem, timing, solution, buyer, and the full score. Pro adds how it makes money, the one risk that could kill it, and the full kit that carries Promptleak from an empty folder to a running MVP.
More like Promptleak
All 25 Dev tools ideasBuild Promptleak, not just read about it
You have the problem, the timing, the solution and the buyer. A plan opens how it makes money, the risk that kills it, and the kit that takes it to a running MVP.
Start building Promptleak