Built for Replit apps. Powered by an AI you can talk to.

Stop guessing if your app
is actually working.

Backcheck is the monitoring tool built for Replit deployments. It watches what your users see, writes its own alerts, and answers your questions in plain English — no dashboards required.

Get homegrown monitoring — $19/mo See how it works
Why Backcheck

UptimeRobot tells you it's up.
Backcheck tells you what's actually happening.

Built for Replit
Speaks your stack. Knows about .replit.app domains, deployment quirks, and how Replit apps actually fail.
AI you can chat with
Ask "is my app okay?" in plain English. The Backcheck assistant reads your live data and answers. No graphs to interpret.
Alerts written by an agent
Not templated. GPT-4o composes each notification with context, tone, and severity. Calm when calm. Urgent when urgent.
Catches the 200 OK lie
Server returns success but your page is broken? Backcheck scans real content for required and forbidden words.
The Problem

The 200 OK Lie

Your server says everything is fine. Your users see something else.

200 OK + Login page shows "undefined"

Your uptime monitor sees a healthy response. Your users see a broken app. Backcheck scans the actual page content and catches this.

200 OK + SSL expires in 3 days

The page loads fine today. In 72 hours, browsers show a security warning and users leave. Backcheck checks your certificate and warns you early.

200 OK + Page content changed unexpectedly

Someone deployed the wrong branch. The homepage now shows a staging environment. Backcheck fingerprints your pages and alerts when content changes.

What It Does

25 features. Zero dashboards.

Every feature exists because of a specific failure mode. Nothing extra.

Liveness checks
Real HTTP requests every hour, the same way a browser would visit your app.
Content scanning
Biotics (words that should be there) and warnings (words that shouldn't). Catches the 200 OK lie.
Page change detection
Fingerprints page content between checks. Catches bad deploys, hacked pages, wrong environments.
SSL monitoring
Checks certificate expiration via TLS handshake. Configurable warning threshold.
Slow response tracking
Only flags after 2+ consecutive slow checks. Ignores single spikes.
Retry before alert
Retries once after 3 seconds before declaring anything down. No false alarms from network blips.
Alert tone escalation
First failure is calm. Repeat failures get urgent. Ongoing issues get brief. Prevents alert fatigue.
Grouped failure detection
When multiple apps fail together, flags a possible shared dependency issue in one notification.
AI-composed emails
GPT-4o writes severity-matched notifications. Not templates — real, context-aware messages.
Webhook support
Slack, Discord, or any HTTP endpoint. Auto-detects platform and formats accordingly.
Weekly Pulse
Once per week: total checks, issues found, downtime incidents. Proof the tool is alive during quiet weeks.
Alert-only mode
Only hear from Backcheck when something is wrong. Silence means healthy.
How It Works

One environment variable. That's the config.

# Add your apps APP_URLS="My SaaS|https://myapp.com|+welcome;-error, Client Site|https://client.com|+portfolio, API|https://api.myapp.com"
1

Set your URLs

Name, URL, and optional content signals. One line per app. Comma-separated.

2

Publish

Backcheck runs on a cron schedule. Default: every hour. No servers to manage.

3

Get notified

Email, Slack, or Discord. Only when something needs your attention.

Getting Started

Up and running in 2 minutes.

No accounts, no onboarding flow, no integrations page. Just environment variables.

1

Add your apps

Set the APP_URLS environment variable. Format:
Name|URL|+biotic;-warning

2

Choose your notification style

Set NOTIFY_MODE=alert-only to only hear when something breaks. Leave it unset for all-clear confirmations too.

3

Optional: Add webhooks

Set WEBHOOK_URL to a Slack, Discord, or any HTTP endpoint. Backcheck auto-detects the platform.

4

Publish and forget

Backcheck runs every hour by default. Change the schedule with SCHEDULE_CRON_EXPRESSION if you want.

# Quick reference: all environment variables # Required APP_URLS="My App|https://myapp.replit.app|+welcome;-error" # Optional NOTIFY_MODE=alert-only # or "all" (default) WEBHOOK_URL=https://hooks.slack.com/... SSL_WARN_DAYS=14 # days before cert expiry to warn SCHEDULE_CRON_EXPRESSION=0 * * * * # default: every hour
# APP_URLS format examples # Basic: just a URL https://myapp.replit.app # Named: Name|URL My App|https://myapp.replit.app # With content signals: Name|URL|signals My App|https://myapp.replit.app|+welcome;+login;-error;-maintenance # Multiple apps: comma-separated App 1|https://app1.replit.app|+home, App 2|https://app2.replit.app|-error, API|https://api.myapp.com
What are biotics and warnings?
Biotics (+) are words that should be on the page. Like vital signs. If "welcome" disappears from your homepage, something is wrong.

Warnings (-) are words that should not be on the page. If "error" or "maintenance" shows up, Backcheck catches it even though the server returned 200 OK.
Pricing

One plan. Set up by hand.

No tiers. No usage limits. No surprise bills. We run Backcheck for you.

Managed Backcheck
$19/month
Everything included. Cancel anytime.
✓Up to 25 monitored URLs
✓Hourly content-aware checks
✓AI-composed email + webhook alerts
✓SSL expiration warnings
✓Weekly Pulse summaries
✓Chat assistant access
✓White-glove setup (we configure it for you)
We reply within 1 business day with your setup link.
Want to self-host? It's open source on GitHub (BSL 1.1).
Philosophy
"Backcheck watches your apps the way you would — if you had time."

Built for solo devs, freelancers, small teams. The people who ship things and move on.

Hourly checks
Dashboards
Email + webhooks
Login required
Content-aware
Per-feature pricing
Alert-only mode
Alert fatigue
Backcheck Assistant
Ask anything
Hey. I'm the Backcheck assistant — built to watch Replit apps. Ask me about app status, how monitoring works, or what you get for $19/mo. I got your back.