Sentry - Error tracking that doesn't suck

Sentry catches crashes and tells you why your code broke. No more debugging production issues from useless log files or angry user emails from customers saying "your site is broken."

Started in 2008 as an open-source project by some Django developers who got tired of checking log files every 5 minutes. Now it's used by over 130,000 teams including Disney+, Slack, GitHub, and Atlassian - basically anyone who's sick of playing "guess what the fuck crashed now" at 3am while their boss is texting them about downtime.

Error Monitoring That Actually Works

The core thing Sentry does is catch exceptions and crashes across 100+ languages and frameworks. When something breaks, you get the actual stack trace, the commit that caused it, and which users were affected. No more digging through GB of logs to find one useful line.

Error grouping works most of the time, but occasionally it groups completely unrelated shit together - like putting database timeouts in the same bucket as frontend JS errors. I've spent 20 minutes wondering why my Postgres connection issues keep mentioning XMLHttpRequest until I realized Sentry thinks they're the same problem. Fixable through fingerprinting rules but you shouldn't have to debug your monitoring tool.

Performance Monitoring (When It Doesn't Slow You Down)

Performance monitoring finds the slow database queries that make your users wait 10 seconds for a page to load. It's basically a profiler that works in production without killing performance (usually adds ~2-5ms overhead per request).

The transaction tracing shows you exactly which API call is taking forever - usually it's that database query you wrote 6 months ago that worked fine with 10 users but shits the bed with 10,000. Nothing like seeing a 30-second SELECT query that you thought was "fast enough" when you wrote it.

Session Replay: Useful for Frontend, Useless for APIs

Session replay records what users actually did when your frontend exploded. You get a video-like playback of mouse movements, clicks, and form inputs (with PII scrubbed automatically).

This is genuinely helpful for frontend bugs where users report "it doesn't work" without any other context. But if your issue is backend logic or API failures, session replay won't help you at all.

Recent Features (Some Actually Useful)

Seer AI Debugging - Available now for $18/month extra. The AI looks at your stack traces and suggests fixes. Great for "Cannot read property 'id' of undefined" errors but completely useless when your race condition only happens on Tuesdays during peak traffic. Don't expect magic - it's still just pattern matching on common bugs.

Logs Integration - Recent logs integration finally correlates log entries with errors automatically, which is nice when it works. Pricing starts at $0.50/GB. Setup can be finicky with custom log formats.

Uptime Monitoring - Added basic uptime checks for $1/alert. It's not as sophisticated as dedicated uptime services, but good enough if you just need "is my site responding."

AI Agent Monitoring - Recently added for tracking LLM applications. Monitors token usage, model latency, and agent workflows. Early days, but useful if you're building AI stuff.

The platform handles billions of events daily and has a 99.9% uptime SLA, which is pretty solid. When Sentry goes down, you really notice it - suddenly you're debugging blind again.

But before you commit to Sentry, you need to understand how it stacks up against alternatives - and more importantly, what it actually costs at scale.

130,000+ teams use Sentry because when your app crashes in production at 2am, you don't want 15 charts. You want to see exactly which line of code broke, in which commit, and how to fix it. Sentry does that.

Who Actually Uses It

Big Tech - Slack, GitHub, Atlassian, and Cloudflare all rely on Sentry. When GitHub's issue tracker goes down, they need to know immediately which service failed and why - not dig through log files for 30 minutes.

Media at Scale - Disney+ uses Sentry because when your streaming app crashes during the season finale of The Mandalorian, millions of Star Wars fans will burn down the internet. Traditional log-based debugging takes hours while Twitter explodes - Sentry shows you the exact crash in seconds so you can fix it before the death threats start.

Mission-Critical Apps - Instacart depends on Sentry because grocery delivery apps can't just "be down for a bit." Every error directly impacts revenue. When checkout breaks, they know about it before customers start calling support.

Business Tools - Companies like Airtable and Monday.com use Sentry because their customers run their entire businesses on these platforms. Downtime isn't just inconvenient - it costs their customers money.

The Numbers Behind the Adoption

Sentry hit $128 million ARR by end of 2023 because developers got tired of spending 2 hours debugging what should be a 5-minute fix. When your app crashes at 3am and you're grep-ing through 50GB of logs while users are screaming on Twitter and your phone won't stop buzzing with PagerDuty alerts, you'll pay anything for actual answers.

Here's Sentry's architecture if you're into that kind of thing:

Sentry Multi-Region Architecture:

Frontend UI → Control Silo (Global) + Region Silos
                ↓                    ↓
         Control Postgres      Regional Postgres + Event Data
              (Users, Orgs)         (Project Data, Events)

Event Flow: App → Load Balancer → Relay → Kafka → Sentry Workers → Snuba → ClickHouse

Basically, your errors go through a bunch of servers before ending up in a database that's actually useful.

The growth comes from practical necessity: microservices make debugging harder, user expectations for uptime keep increasing, and modern apps break in more creative ways than ever before. Traditional log-based debugging doesn't scale.

Why Sentry Wins vs Competitors

Developer-First Approach - Unlike Datadog's 47 different dashboards that tell you everything except how to fix the problem, Sentry just shows you the broken code and the stack trace. That's it. That's why developers prefer it.

Open Source Foundation - Teams can start with self-hosted Sentry for free, then migrate to SaaS when they get tired of managing infrastructure. It's a natural progression from "let's try this" to "we depend on this."

Honest Pricing - Sentry's pricing is straightforward per-event billing. You know what you'll pay based on your error volume. Datadog and New Relic pricing requires a spreadsheet and a crystal ball to figure out.

Focus on Fixing, Not Monitoring - When your app crashes in production, most APM tools tell you "something is wrong somewhere." Sentry tells you exactly what's wrong and usually which commit caused it. The difference is 5 minutes to fix vs 2 hours of investigation.

The reason Sentry keeps growing is simple: it solves the actual problem developers face every day. When you're debugging at 3am, you don't want beautiful charts. You want answers.

But theory is one thing - practical implementation is another. Here are the real questions developers ask when evaluating Sentry.