Comparison
Fonsitor vs Sentry
Honest comparison -- when to choose each
Feature Matrix
Side by side
A lightweight first-party monitor vs the industry-standard error tracking platform.
| Feature | Fonsitor | Sentry |
|---|---|---|
| Price | Free (open source) | Free (5K events); Team $26/mo; Business $80/mo |
| Target platform | Kotlin Multiplatform (Android, iOS, Desktop, Server) | 40+ languages and frameworks |
| Self-hosted | Yes -- full self-hosted option | Yes (self-hosted available, complex setup) |
| First-party Kotlin/KMP | Native KMP library, zero platform bridging | Java/Android SDK; no KMP-native SDK |
| SDK size overhead | Lightweight (~50 KB) | ~300-500 KB (varies by platform) |
| Error tracking | Crashes, exceptions, breadcrumbs | Crashes, exceptions, breadcrumbs, stack traces |
| Performance monitoring | Basic timing metrics | Full APM: traces, spans, throughput, load times |
| Session replay | No | Yes -- visual session replay |
| AI debugging | No | Seer AI agent ($40/user/mo add-on) |
| A/B testing integration | No | Feature flags and release health |
| Alerting | Webhook-based alerts | Rich alerting: Slack, PagerDuty, email, custom rules |
| Data retention | Unlimited (self-hosted) | 30 days (free); 90 days (Team/Business) |
| Setup complexity | Single Gradle dependency | SDK + DSN config + source maps |
| Vendor lock-in | None -- self-host, export anytime | Event-based billing, data in Sentry cloud |
When to choose
Different tools, different strengths
The right choice depends on your stack, scale, and budget.
Choose Fonsitor when...
- You build with Kotlin Multiplatform and want a native KMP SDK
- You want zero cost -- free and open source, no event caps
- You need full data ownership with self-hosting
- A lightweight SDK with minimal app size impact matters
- You want simple setup -- one Gradle dependency, done
- Your error monitoring needs are straightforward (crashes + errors)
Choose Sentry when...
- You work across many languages (Python, JS, Go, Ruby, etc.)
- You need full APM: performance traces, spans, throughput metrics
- Session replay and visual debugging are important to your workflow
- You want AI-powered debugging assistance (Seer)
- Your team relies on rich integrations (Slack, PagerDuty, Jira)
- You operate at scale and need enterprise features (SSO, RBAC)
KMP error monitoring. Free. Self-hostable.
Add Fonsitor to your Kotlin Multiplatform project in under a minute.