Monitoring SaaS in 2026 splits into four jobs: error tracking (Sentry), session replay + product analytics (PostHog), application logs (Better Stack, Logtail), and full observability (Datadog or Grafana stack). Get all four right and your debug time drops 60–80%. Get them wrong and either you're flying blind or paying $4k/month for telemetry on a 100-user app.
The 4 categories
| Category |
Best free |
Best paid |
Skip |
| Error tracking |
Sentry (5k err/mo) |
Sentry Team $26/mo |
Custom logging schemes |
| Session replay |
PostHog (1M events/mo) |
LogRocket $99/mo |
FullStory at indie scale |
| Logs |
Better Stack (1 GB/mo) |
Logtail $24/mo |
Splunk for SMB |
| Full observability |
Grafana self-hosted |
Datadog (varies) |
Datadog at small scale |
Best error tracking — Sentry
EDITOR'S PICK
Sentry
5,000 errors/mo free, $26/mo Team adds session replay + performance. Industry default for error tracking. SDK for every framework. Source maps, breadcrumbs, release tracking — the works. Self-hostable if you want full control.
Visit Sentry →
For most SaaS: free tier is enough until ~5k MAUs. Upgrade to Team when you cross.
Best for session replay + product analytics — PostHog
PostHog combines product analytics, session replay, feature flags, and A/B tests in one tool. Free tier covers 1M events/month — generous for early-stage. Self-hostable. We covered the broader category in Best free alternatives to paid developer tools 2026.
When Datadog makes sense
At 50+ hosts and serious production traffic, Datadog's integrated APM + logs + metrics is genuinely best-in-class. At 1–5 hosts and indie scale, it's massive overkill that easily costs $400–$2,000/month for the same value Grafana stack delivers free.
What's NOT worth your money
- Datadog for indie SaaS — bills creep from $0 to $400/mo in one quarter
- Splunk for anything but enterprise — pricing model assumes massive log volume budgets
- Custom logging frameworks when Better Stack at $24/mo solves it
- Multiple session replay tools — pick one (PostHog or LogRocket)
- Pingdom-style uptime monitoring when Better Stack or BetterUptime have free tiers
FAQ
What's the cheapest credible monitoring stack?
Sentry free + PostHog free + Better Stack free. Total $0/mo. Covers a typical pre-revenue SaaS.
When should I upgrade to paid Sentry?
When you regularly hit the 5k errors/month limit AND those errors matter. If you're noisy, fix the noisy errors first.
Can I use one tool for everything?
PostHog comes closest — it does product analytics, session replay, feature flags. Add Sentry separately for error tracking.
Best for Next.js / React?
Sentry has best-in-class Next.js integration. PostHog has React SDK. Both work seamlessly.
Should I self-host Sentry?
Only if your error volume is genuinely high (>50k errors/mo) AND you have ops capacity. Otherwise hosted Sentry's $26/mo is fair value.
What about cron job monitoring?
Cronitor or Healthchecks.io — both have free tiers, simple "this should ping me every X minutes" check.
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