AppSignal vs JustAnalytics: Ruby and Elixir APM or Full-Stack Frontend Observability
AppSignal dominates Ruby/Elixir APM. JustAnalytics covers frontend replay, analytics, and uptime. Honest breakdown of which fits your stack.
Three months ago I inherited a Rails monolith with zero observability. The previous team had ripped out New Relic after a $2,400 monthly invoice scared the CFO. They replaced it with... nothing. Just Honeybadger for exceptions and crossed fingers.
My first week, a checkout flow started timing out. Users complained. Support tickets piled up. And I sat there staring at Rails logs trying to figure out which database query was slow. No traces. No performance baselines. No idea if this was a new regression or a Tuesday.
That weekend I evaluated AppSignal and JustAnalytics side by side. Added both to staging. Ran load tests. Watched the dashboards fill up. (Also ate too much pizza and slept maybe four hours. Not proud.)
Here's the thing nobody told me upfront: these tools solve different problems. AppSignal is a backend APM specialist — it instruments Ruby, Elixir, Node, and Python with surgical precision. JustAnalytics is a frontend-first consolidation platform — it bundles analytics, session replay, errors, and uptime into one script. Comparing them head-to-head is like comparing a backend debugger to a full-stack dashboard. Both useful. Not interchangeable. If you're evaluating multiple options, our observability tool comparison guide covers more alternatives.
Quick Verdict
TL;DR: AppSignal wins on Ruby/Elixir backend depth. JustAnalytics wins on frontend coverage and tool consolidation.
If your stack is Rails or Phoenix and backend performance is your main headache — slow queries, background job failures, memory bloat — AppSignal is purpose-built for that. The Ruby agent auto-instruments ActiveRecord, Sidekiq, and every Rails controller action without touching your code. The Elixir integration is similarly polished. For backend APM in those ecosystems, AppSignal is one of the best options available.
If your stack is frontend-heavy — React, Next.js, Vue — and you need session replay plus analytics plus uptime monitoring alongside error tracking, JustAnalytics covers more surface area. You won't get the same Rails-specific depth, but you'll get a single script that replaces five separate tools.
The honest question: What's actually breaking? If it's database queries and background jobs, AppSignal. If it's checkout flows where you need to see what users clicked before the error, JustAnalytics.
Feature Comparison
| Feature | JustAnalytics | AppSignal |
|---|---|---|
| APM / performance monitoring | Yes (OpenTelemetry-native, P95/P99, service maps) | Yes (native agents for Ruby, Elixir, Node, Python) |
| Error tracking | Yes (source-mapped stacks, issue grouping, rage-click detection) | Yes (exception tracking with deploy correlation) |
| Session replay | Yes (pixel-perfect DOM replay with privacy masking) | No |
| Web analytics | Yes (pageviews, funnels, UTM, cohorts, attribution) | No |
| Uptime monitoring | Yes (HTTP checks, SSL, status pages, cron alerts) | Yes (endpoint monitoring, alerts) |
| Structured logs | Yes (ingestion, filtering, alerting) | Yes (full-text search, real-time streaming) |
| Host metrics | Via OpenTelemetry | Yes (CPU, memory, disk, network) |
| Ruby/Rails depth | Via OpenTelemetry (manual setup) | Native agent (auto-instruments AR, Sidekiq, controllers) |
| Elixir/Phoenix depth | Via OpenTelemetry | Native agent (auto-instruments Ecto, Phoenix, Oban) |
| Frontend JavaScript | Yes (under-5KB script, Web Vitals, errors) | Yes (JS agent for errors, limited) |
| Free tier | $0/mo — 100K events, 1 site, 6mo retention | $0/mo — 50K requests, 1GB logs, 5-day retention |
| Paid starting plan | Pro $49/mo — 1M events, 5 sites, all features | $23/mo — 250K requests, all features |
| AI integrations | AI Command Center ($25/mo add-on) — MCP for Claude/Cursor | MCP server for Claude, Cursor, Zed |
The shapes are different. AppSignal is deeper on backend languages — especially Ruby and Elixir where their native agents auto-instrument framework internals. JustAnalytics is wider on frontend surfaces — replay, analytics, and browser-side coverage that AppSignal doesn't touch.
Where AppSignal Wins: Backend Language Depth
AppSignal's Ruby support is exceptional. Annoyingly good, actually.
Rails auto-instrumentation is nearly magical. Add the gem, set an API key, deploy. That's it. Traces for every controller action, every ActiveRecord query (with SQL explain plans), every Sidekiq job. No manual spans. The agent knows Rails internals and instruments them automatically.
I installed AppSignal on that inherited monolith in about 12 minutes. First deploy, the dashboard lit up with slow query traces I'd been hunting for days. A N+1 query in the orders controller. A Sidekiq job timing out because someone forgot to set an HTTP timeout. AppSignal surfaced it immediately.
Elixir support is similarly polished. Phoenix, Ecto, Oban — all auto-instrumented. AppSignal is one of the few APM tools that treats Elixir as a first-class citizen instead of an OpenTelemetry afterthought.
Background job monitoring is excellent. Sidekiq, Resque, DelayedJob for Ruby. Oban for Elixir. Job duration, failure rates, queue depths. When a job fails, you get the backtrace and arguments. We have job monitoring too, but AppSignal's is more mature.
Host metrics included. CPU, memory, disk, network — in the same dashboard as APM traces. JustAnalytics can ingest host metrics via OpenTelemetry, but requires manual setup. AppSignal handles it automatically. I'm a bit jealous of their onboarding flow here, honestly.
Straightforward pricing. $23/month for 250K requests, all features included. $59/month for 3M. $239/month for 25M. No per-host charges. They explicitly promise not to bill you extra even if you exceed your plan tenfold. (We've written about observability pricing models for the full breakdown.)
If your primary problem is "why is my Rails app slow" or "why are my Phoenix jobs failing," AppSignal is purpose-built for that.
Where JustAnalytics Wins: Frontend Coverage and Consolidation
Here's the gap in AppSignal's coverage: the browser.
AppSignal has a frontend JavaScript agent for errors. That's about it. No session replay. No web analytics. No conversion funnels. No UTM tracking. If you need to understand what users actually do on your site — not just whether the backend threw an error — AppSignal expects you to add other tools.
Session replay is the big one. When a user reports "checkout is broken," the ideal workflow is: find the error, click into the session, watch what they did. AppSignal gives you the error. JustAnalytics gives you the replay too. DOM replay with privacy masking. Rage-click detection. When support says "I can't reproduce it," click the replay link and watch it happen. We covered session replay best practices for teams concerned about PII.
Web analytics bundled. Pageviews. Funnels. Cohort retention. Attribution. UTM tracking. One dashboard correlates "user landed from Google Ads campaign X, hit product page, started checkout, error on payment step, abandoned." AppSignal can't tell you the marketing attribution or funnel step. If your team runs paid campaigns, ClickzProtect handles click fraud detection with the same event-correlation approach.
Five tools in one script. Analytics (replaces GA4), error tracking (replaces Sentry for basics), APM (replaces basic Datadog), session replay (replaces LogRocket), uptime (replaces Pingdom). AppSignal covers APM, errors, logs, and uptime — four of five. No analytics, no replay.
The script is under 5KB. For frontend performance, bundle size matters.
OpenTelemetry-native backend support. We don't have AppSignal's deep Ruby/Elixir agents — but we support OpenTelemetry. Point traces at our endpoint. Won't be as automatic as native agents. Will work across any language OTel supports. (Yeah, I know — "just add OpenTelemetry" is easier said than done. We're working on better Rails auto-setup. Not there yet.) Our OpenTelemetry setup guide walks through the configuration.
The Real Question: Backend-First or Frontend-First?
This comparison isn't about which tool is "better." It's about which problem you're solving.
Backend-first teams (Rails, Phoenix, Django): Your bugs live in database queries, background jobs, API response times. For this pattern, AppSignal's backend depth matters more than frontend replay. Auto-instrumented Rails traces beat manual OpenTelemetry setup.
Frontend-first teams (React SPAs, Next.js, Vue/Nuxt): Your bugs live in JavaScript, browser APIs, client-side state. Session replay and frontend error tracking matter more than Rails query traces. AppSignal's backend depth doesn't help when the bug is in your React state management.
Hybrid teams: You need both. Do you want best-in-class backend APM (AppSignal) plus separate frontend tools (LogRocket, GA4, Pingdom), or consolidated coverage (JustAnalytics) that handles frontend well and backend adequately?
Consolidation has real value at 2am. One dashboard instead of four. But specialization has value too — AppSignal's Rails traces are genuinely better than what we offer via OpenTelemetry.
I'll be honest: if you asked me to debug a slow ActiveRecord query right now, I'd probably reach for AppSignal. Hurts to say that about a competitor. But it's true.
Pricing Breakdown (as of June 2026)
JustAnalytics:
- Free: $0/mo — 1 site, 100K events/mo, 6mo retention. Analytics only.
- Pro: $49/mo ($39/mo annual) — 5 sites, 1M events/mo, 1yr retention. Errors, replay, APM, uptime, logs.
- Enterprise: custom — unlimited. SSO/SAML, SLA, dedicated infrastructure.
- AI Command Center: $25/mo add-on (requires Pro+).
AppSignal:
- Free: $0/mo — 50K requests/mo, 1GB logs, 5-day retention.
- 250K: $23/mo — all features.
- 3M: $59/mo — all features.
- 25M: $239/mo — all features.
AppSignal charges by request volume. No per-host fees. No feature gating. They promise not to bill you extra even if you exceed your plan by 10x.
The consolidation math: AppSignal ($23/mo) plus GA4 plus LogRocket ($99/mo) plus Pingdom ($15/mo) = $137/mo minimum. JustAnalytics Pro = $49/mo for all surfaces.
But if you only need backend APM and logs, AppSignal at $23/mo is cheaper.
Who Should Pick What
Running Rails or Phoenix, backend APM is main need: AppSignal. Full stop. Native agents auto-instrument framework internals. Traces surface slow queries immediately. For Ruby and Elixir backend observability, it's one of the best.
Frontend-heavy, need session replay plus analytics: JustAnalytics. AppSignal doesn't do replay or web analytics. JustAnalytics bundles it in one script.
Hybrid team needing both: Evaluate the tradeoff. AppSignal plus LogRocket/GA4 gives best-of-breed on both sides but costs more. JustAnalytics gives consolidated coverage with adequate Rails support via OpenTelemetry.
Early-stage, need predictable costs: Both have free tiers. AppSignal's $23/mo is cheaper for pure APM. JustAnalytics Pro at $49/mo is cheaper if you'd otherwise need multiple tools.
Running Elixir specifically: AppSignal. Native Phoenix, Ecto, and Oban instrumentation. Few APM vendors treat Elixir as first-class. Frustrating, because Elixir's concurrency model makes it perfect for tracing — but most vendors ignore it.
Our Honest Take
AppSignal is excellent at what it does. Ruby and Elixir APM with deep auto-instrumentation. Logs, uptime, host metrics — all bundled with honest pricing. If I were building a Rails app and only needed backend observability, AppSignal would be on my shortlist.
But AppSignal doesn't pretend to be a frontend platform. No replay. No analytics. When the bug is "users are abandoning checkout" and you need to see what they clicked, AppSignal shrugs. That's not a criticism — it's a scope definition. They picked a lane. Respect.
We chose the opposite. JustAnalytics covers frontend surfaces AppSignal doesn't touch — replay, analytics, browser-side errors — while also handling APM, logs, and uptime. Our Rails support isn't as polished. Real talk: if Rails auto-instrumentation depth is your deciding factor, AppSignal wins.
The question isn't which tool is "better." It's which problem matters more: backend traces or frontend context. You know your stack. Pick accordingly.
More comparison posts on the JustAnalytics blog — including Raygun alternative, Highlight.io comparison, and consolidating five tools. For teams running paid acquisition, VeloCalls tracks pay-per-call and ClickzProtect catches click fraud.
Frequently Asked Questions
Does AppSignal have session replay?
No. AppSignal focuses on backend APM, error tracking, logging, and uptime monitoring. It has a frontend JavaScript agent for error tracking but no session replay. JustAnalytics includes pixel-perfect DOM replay with privacy masking as part of the Pro plan at $49/mo.
Can I use AppSignal for web analytics and conversion funnels?
No. AppSignal is APM-focused — it tracks performance metrics, errors, and logs, not marketing analytics. You'd need to add GA4, Plausible, or another tool for pageviews, UTM tracking, and funnels. JustAnalytics bundles web analytics with errors, APM, replay, and uptime in one script.
Is AppSignal better than JustAnalytics for Ruby on Rails?
For deep Rails-specific instrumentation — yes. AppSignal's Ruby agent auto-instruments ActiveRecord, ActionController, Sidekiq, and other Rails internals with minimal setup. JustAnalytics supports Rails via OpenTelemetry but requires more manual configuration. If backend APM depth is your priority, AppSignal wins. If you also need frontend replay and analytics, JustAnalytics covers more ground.
What's the pricing difference between AppSignal and JustAnalytics?
AppSignal starts at $23/mo for 250K requests, with a free tier at 50K requests. JustAnalytics Free is $0/mo for 100K events (analytics only), and Pro is $49/mo for 1M events including errors, APM, replay, uptime, and logs. AppSignal is cheaper for pure backend APM. JustAnalytics is cheaper if you'd otherwise need separate tools for analytics, replay, and uptime.
Try JustAnalytics
All-in-one observability in one under-5KB script: cookieless analytics + error tracking + APM + session replay + uptime + structured logs. Replaces GA4 + Sentry + Datadog + Pingdom + LogRocket. Free tier (100K events/mo), Pro $49/month ($39 annual).
Author at JustAnalytics.