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App errors

Catch errors before your users do.

When something breaks in production or in your terminal, Faundr explains the error in plain language and shows how many users hit it and where it started. You get an alert in Slack or Discord, and your AI fixes it.

Get started free See what every error includes
What you avoid

Every unseen error is a lost user. And most of them leave without telling you.

  • Your users find the bug first.

    Checkout broke at 7 PM, and you only found out hours later when a customer messaged you. Everyone who hit that error is a lost sale.

    Faundr checks

    • Production errors, with page and version
    • How many people hit each error
    • Alerts in Slack or Discord
    • Sudden error spikes

  • Your site goes down at 3 AM.

    Nobody’s watching in the middle of the night. Without an alert, the site stays down until someone complains.

    Faundr checks

    • Uptime checks every 5 minutes
    • Alerts when it goes down and comes back
    • Total downtime
    • Counts toward the launch verdict

  • You fix it, and the bug comes back.

    The fix looked right, but the error resurfaces in the next release. With no history, it looks brand new.

    Faundr checks

    • Fixed errors that come back reopen automatically
    • Marked resolved only after the next deploy
    • Command errors close once the command passes
    • Your AI gets nudged when stuck on one error
Both sides

Faundr catches errors in your code. It also watches your live app and tells you the moment something breaks.

Terminal · commands

Errors from your agent’s commands

Builds, type checks, tests, lint and scripts, in any language your project uses. Every failure becomes an E-n with the file, line and output snippet, and closes automatically once the same command passes.

  • npm run buildE-31 · Cannot find module ./shipping
  • npx tsc --noEmitE-30 · TS2345 in coupon.ts:18
  • npx vitestpassed · E-28 closed
Live app · shop.com

Production errors

Your app uses Sentry’s free SDK for its language, pointed at Faundr. No Sentry account needed. From Next.js and Expo to Django, Laravel, Flutter, Go, Spring, .NET and Rust.

  • /checkoutE-12 · 23 users
  • /product/[id]E-6 · 2 users
  • api/signupE-9 · regressed
Every error, explained

Understand any error, no coding required. Fix them all with a single command.

Errors / E-12
Production23 usersv1.4.2

TypeError: total is undefined

In plain language

The code tried to read a total from something that doesn’t exist.

Common cause

Some data came through empty, in this case the cart after an expired coupon.

How to fix

Handle the empty cart before calculating the total.

Copy prompt for your agent /faundr:error-fix E-12

What the user did first

  1. opened /product/iced-coffee
  2. clicked "Add to cart"
  3. applied coupon COFFEE10 (expired)
  4. opened /checkout
  5. clicked "Pay"

Where it broke, and where it came from

src/checkout/total.ts:41 · calculateTotal()

You see the original source even on a minified site, with nothing to upload.

yesterday’s session, 6:40 PM · "enable the discount coupon"

The commit that changed this line, and the prompt behind it.

Your AI fixes what you show it. Faundr shows it what you missed.

Without Faundr, your AI only hears about an error when you paste it into the chat. With Faundr, every error arrives explained, with who hit it, where it started and a fix command ready to run.

AI agent aloneWith Faundr
Production errorA user tells you.Lands in your dashboard and Slack, with how many users hit it.
The error messageCryptic, pointing at minified code.In plain language, with the original source.
Where the error came fromNobody knows.The session, the prompt and the commit behind it.
A fixed error comes backLooks like a brand-new error.Reopens automatically as a regression.
Site downSomeone complains.Checked every 5 minutes. Two failures in a row trigger an alert.
A build or test failsLost in terminal scrollback.Becomes an E-n and closes itself when the command passes.
AI stuck on one errorKeeps retrying forever.On the third try, it stops and digs for the root cause.
Error tracking toolA Sentry account and plan.Sentry’s SDK, straight into Faundr. No extra account.
How it works

Four ways to watch your app. From terminal commands to your live site.

Capture, explanations and alerts run without AI. Connecting your live app takes one command: /faundr:errors-setup.

  1. In the terminal

    Your agent’s commands.

    Failed builds, type checks, tests, lint and scripts become E-n issues and close when they pass again.

  2. In production

    Your users’ errors.

    Sentry’s SDK sends every error to Faundr, with the page, version and what the user did first.

  3. Every 5 minutes

    Is the site up?

    Two failures in a row trigger "Site down". When it recovers, the error closes itself.

  4. On your phone

    Alerts that matter.

    New errors, regressions, spikes and downtime go straight to Slack or Discord.

From error to fix

One click points your AI at the right spot. It goes straight to the root cause.

The command hands your AI the error, the page, the original source and what the user did first. It fixes the bug without burying it in an empty catch, and production errors close only once the next release is live.

Errors: TypeError: total is undefined.

Your skills

Use your own debugging skill. Faundr connects to it and shows every bug it finds.

Connect the skills you already use, from any author or plugin, with /faundr:skills. When one runs, every bug it finds becomes an E-n in your Errors dashboard, tagged with the skill’s name.

Workflows · Skills
  • /debug Plugin Connected · Errors

    Tracking down a bug step by step

  • /write-copy Project

    Writing or improving page copy

Errors · open
  • E-33Webhook retry charges the user twicesrc/server/stripe-webhook.ts:58via /debug
  • E-32Session expires mid-checkout and empties the cartsrc/lib/session.ts:17via /debug
  • E-30TS2345 in coupon.tssrc/coupon.ts:18tsc
  • Counted like Faundr’s own. Same list, same E-n numbering, same /faundr:error-fix E-n when you want it fixed.
  • Closes itself. Run the skill again and whatever it no longer finds is marked resolved.
  • Each skill minds its own. A skill only closes what it reported, never Faundr’s errors or another skill’s.
Privacy

Your users’ data stays out. Masked before anything is stored.

  • password=hunter2password=[filtered]
  • emma@shop.com[email]
  • 4111 1111 1111 1111[card]
  • 73.162.40.7[ip]

Passwords, tokens, cards, emails and IPsget masked before the error is saved.

One anonymous ID per user.Faundr counts how many users hit an error without knowing who they are.

No form data, cookies or request bodies.Page URLs are sent without query parameters.

Supported languages

Reading command errors works in each language with nothing to install. For the live app, /faundr:errors-setup adds Sentry’s free SDK for your language.

Command errors

  • JavaScript & TypeScript
  • React Native
  • Vue
  • Angular
  • Svelte & Astro
  • Python
  • Flutter & Dart
  • PHP
  • Go
  • Java
  • Kotlin
  • C#
  • Rust
  • C
  • C++
  • Docker
  • CSS

Errors in the live app

  • JavaScript & TypeScript
  • React Native
  • Vue
  • Angular
  • Svelte & Astro
  • Python
  • Flutter & Dart
  • PHP
  • Go
  • Java
  • Kotlin
  • C#
  • Rust
  • C
  • C++
  • HTML

See what each part covers, language by language

FAQ

Do I need a Sentry account?

No. Your app uses Sentry’s free SDK, pointed at Faundr instead. Already on Sentry? You can import your open errors.

Does it work with my app?

Command errors are picked up in every language Faundr supports, with nothing to install. For the live app: Next.js, React, Vue, Nuxt, Angular, SvelteKit, TanStack Start, Remix, Node, Cloudflare Workers, Expo, plain HTML sites, Python (Django, Flask, FastAPI), Flutter and Dart, PHP and Laravel, Go, Java and Kotlin (Spring, Android), .NET, Rust and C/C++. The /faundr:errors-setup command adds Sentry’s SDK for your language, points it at Faundr and sends a test error.

Will it slow my app down?

Faundr only collects errors. It tells the SDK to skip everything else (performance, session replay, sessions), so your app sends the bare minimum.

What if I get flooded with errors?

Up to 300 errors an hour, each one keeps a full sample. Past that, they’re just counted. Past 3,000 an hour, Faundr drops them until the next hour starts.

Does it use my tokens?

No. Capture, plain-language explanations and alerts all run without AI. Only fixes use your AI plan, and only when you ask.

Sleep well with your app live. If something breaks, you’ll be the first to know.

Get started free