Spear the bottleneck.
Harpoon's deterministic engine ranks your real bottlenecks from an actual page load, scores them 0–100, and has an AI explain in plain English exactly what to fix.
Built for the people who own the latency budget.
Four reasons perf, SRE, and platform teams point Harpoon at every release.
Catch regressions before they ship
Diff before/after captures and fail the build when the waterline breaks.
Deterministic, not hallucinated
Same HAR in, same finding IDs out. The engine finds it; the AI only explains it.
Only findings go to the AI
The engine does the analysis; only the structured findings and page metadata are sent to the AI — never your cookies, tokens, or response bodies.
A score you can argue with
A transparent, weighted 0–100. Every point lost traces to a dimension.
From capture to fix in three steps.
Drop a HAR
Drag in a capture from DevTools. Nothing is uploaded to a model.
The engine spears the findings
Deterministic analysis ranks your real bottlenecks and scores them 0–100.
The AI explains the fix
A structured summary becomes plain-English guidance: what to change, what it buys you.
Fail the build before the waterline breaks.
Harpoon diffs before/after captures by canonical URL and crosses the waterline when a release regresses. Drop it in CI and the build fails with the numbers attached.
Honest about where we win — and where we don't.
Harpoon is the affordable, engineer-honest layer on top of your own captures. If you need real-user monitoring or a global synthetic test network, a bigger suite is the better buy — we'll say so.
| Capability | Harpoon $0 free · $39/mo | Synthetic suites DebugBear · SpeedCurve · Calibre | Lab tools WebPageTest · Lighthouse CI |
|---|---|---|---|
| Analyzes your real page load | |||
| Deterministic, request-level findings | |||
| AI plain-English explanations | |||
| CI regression diff — fail the build | |||
| Authenticated, multi-step capture | |||
| Scheduled monitoring + alerts | |||
| Real-user monitoring (RUM) | |||
| Global synthetic test network | |||
| Free tier / starting price |
YesPartialNo
Pricing that scales with what you watch.
Start free with ad-hoc analysis — no signup required. Upgrade when you want Harpoon on every release: scheduled, with an alert the moment the waterline moves.
Drop-in
Ad-hoc analysis
- Manual HAR analysis
- Full Harpoon Score + findings
- AI plain-English explanations
- 3 catches saved
Patrol
MOST POPULARContinuous monitoring
- Everything in Drop-in
- 25 scheduled monitors
- Waterline alerts — Slack, email, webhook
- Regression diffs + CI checks
- 90-day history · 5 seats
Fleet
Org-wide + authenticated flows
- Everything in Patrol
- Authenticated & multi-step captures
- Login-gated dashboards & flows
- Unlimited monitors + seats
- SSO / SAML + audit log
- 1-year retention + priority SLA
14-day free trial on paid plans · cancel anytime · book a 20-min walkthrough
Questions, answered honestly.
Everything a first-time visitor asks before dropping in their first capture.
What is a HAR file?
A HAR (HTTP Archive) is a JSON file your browser's DevTools exports that records every network request a page made — URLs, sizes, timings, and status codes. In Chrome: open DevTools → Network, reload the page, then right-click a request and choose “Save all as HAR”.
Does my HAR get sent to the AI model?
No — the raw HAR is never sent to the AI. Your file is uploaded to Harpoon and analyzed by the deterministic engine; only a small, structured summary of the findings and page metadata is sent to the model to write the plain-English explanation — never your cookies, tokens, query strings, or response bodies.
Do I need to sign up to try it?
No signup required. Drop a HAR on the analyzer and get the full Harpoon Score, findings, and AI explanation instantly. Create an account only when you want to save analyses, monitor on a schedule, or share a report.
What's included in the free tier?
Unlimited manual HAR analysis with the full score, findings, and AI explanations. The free plan keeps your latest 3 saved analyses; paid plans add scheduled monitoring, waterline alerts, longer history, and team seats.
How do the free trial and cancellation work?
Paid plans start with a 14-day free trial. You can cancel anytime from the billing portal; cancel before the trial ends and you are never charged.
Can I run Harpoon in CI?
Yes. The Harpoon CLI and GitHub Action diff a before/after capture by canonical URL and fail the build when a release regresses past your waterline, with the request-level numbers attached to the check.
Do you store my raw HAR?
Raw HARs are kept encrypted only as long as needed to run the analysis and are removed on a retention schedule. The analysis we retain contains only the curated, PII-free findings — never your raw requests.