Sentry vs FlareLog — Which Catches More Cloudflare Worker Crashes?
Sentry sees your SDK errors. FlareLog sees the crashes that kill your Worker before the SDK fires.
TL;DR
Sentry is a great product. It's not a bad choice. But on Cloudflare Workers, it has a fundamental blind spot: it can't see crashes that happen before your code runs. FlareLog's Tail Worker runs out-of-band and captures every crash — CPU timeouts, OOM kills, startup failures — that Sentry misses entirely.
If you need Sentry's specific strengths (listed below honestly), keep it. If you need to catch Worker crashes, monitor your Cloudflare bill, and debug with AI, FlareLog is the better fit. Many teams run both.
Head-to-head
FlareLog
Where FlareLog wins
- +Tail Worker catches crashes Sentry can't see (CPU timeout, memory exhaustion, startup failure)
- +Cost burn alerts for Cloudflare Workers, KV, R2, D1 — Sentry has no cost monitoring
- +MCP server for AI-native debugging in Cursor and Claude Desktop
- +90-day log retention on free tier (Sentry: 30 days)
- +10k logs/month free vs Sentry's 5k error events/month
- +Zero-dependency SDK — Sentry's SDK adds 45KB to your Worker bundle
Where FlareLog falls short
- −No session replay (roadmapped)
- −Smaller integration ecosystem (5 frameworks vs Sentry's 200+)
- −Less mature source map pipeline
- −Newer product — fewer community resources and Stack Overflow answers
Sentry
Where Sentry wins
- +Session replay — Sentry records user DOM interactions, FlareLog doesn't
- +Deep performance profiling with language-specific profilers (Python, Java, Node)
- +Battle-tested source map upload and symbolication pipeline
- +Hundreds of framework integrations (Django, Rails, Spring, Unity, React Native)
- +Superior issue grouping and fingerprinting for deduplication
- +Established enterprise presence with SOC 2, SSO, audit logs
Where Sentry falls short
- −Can't see Worker crashes that happen before your code runs (CPU timeout, OOM, startup failure)
- −No Cloudflare cost monitoring or burn alerts
- −Log retention capped at 30 days on free, 90 days on Team ($80/mo)
- −SDK adds 45KB to your Worker bundle (FlareLog: 0KB — zero deps)
- −No MCP server for AI debugging
- −Pricing scales per-event — 50k events/mo costs $26/mo vs FlareLog's $0
FAQ
Can I use both Sentry and FlareLog together?
Yes. Many teams run Sentry for client-side error tracking (React, React Native) and FlareLog for Cloudflare Worker crash capture and cost monitoring. They don't conflict — Sentry wraps your fetch handler, FlareLog's Tail Worker runs out-of-band. Install both SDKs and they'll capture different layers of your stack.
Is FlareLog a Sentry replacement for large teams?
Not yet. If you need session replay, deep APM/tracing across multiple languages, SOC 2 compliance, or SSO, keep Sentry. FlareLog is built for developers shipping on Cloudflare Workers who want crash capture + cost monitoring + AI debugging without the enterprise overhead. If you outgrow Lovable and hire an SRE team, you may want both.
How does pricing compare?
FlareLog free tier: 10,000 logs/month, 90-day retention, no credit card. Pro: $19/month for 2M logs, cost alerts, Slack notifications. Sentry free tier: 5,000 error events/month, 30-day retention. Team plan: $26/month for 50k events. FlareLog is cheaper at every tier for Cloudflare Workers use cases because we charge per-log, not per-error-event, and include cost monitoring that Sentry doesn't offer at all.
Why can't Sentry see Error 1101?
Sentry's Cloudflare Workers SDK wraps your fetch handler and catches exceptions thrown during request handling. Error 1101 (Worker threw exception) can occur before your fetch handler registers — e.g. during module initialization, or when the runtime kills the Worker for CPU/memory limits. Sentry's captureException never fires because the Worker is already dead. FlareLog's Tail Worker runs out-of-band, after your Worker finishes (or crashes), and receives the execution outcome from Cloudflare's runtime — so it captures crashes that happen before, during, and after your code runs.
Catch the crashes Sentry can't see
Free 10k logs/mo, 90-day retention, Tail Worker crash capture, cost burn alerts. No credit card.
Start logging free →