REDLINE
The device performance floor

Find the slowest device that still has to use your site.

Redline saturates the CPU, floods memory bandwidth, thrashes the layout engine, hammers the compositor and probes the network — right here, in the browser you're holding. In five seconds you'll know which real-world devices will break your site, and the engineering fixes that keep them working. No install, no account, no data leaving the device.

Stress this deviceHow it differs
✦ No install✦ Works offline-first✦ Private by design✦ Free forever tier
Not another load tester

Load testing asks if your server survives. Redline asks if the device does.

k6, JMeter, Locust and Artillery generate traffic to measure server throughput. Lighthouse and WebPageTest audit a single page in a single browser. Redline is the missing piece: it stresses the actual device hardware, then tells you which devices will choke on your site — and what to fix.

Capability
Load testing

k6 · JMeter · Locust · Artillery

Synthetic audit

Lighthouse · WebPageTest

Redline

Device performance floor

What it actually tests
How many concurrent users your server can absorb
How one browser audits one page load
How real device hardware handles your site
Runs anywhere, no install
No — CLI or cloud account required
Web app, but tied to one test runner
Yes — any browser, any device
Real-device hardware stress
No
No
CPU, memory, layout, GPU, network
AI diagnosis tied to the device
No
No
Yes — references your real numbers
Private by design (no data uploaded)
No
No
Yes — runs locally in the browser
CI performance budgets & gating
Yes
Partial
On the team roadmap
✦ For frontend developers✦ For QA engineers✦ For product & marketing✦ Redline vs k6 & load testing✦ Redline vs Lighthouse
The lab

Push it to the redline.

Device under test

Detecting…

Runs entirely on this device. Roughly 5 seconds — the UI will intentionally strain while it works. Nothing is uploaded.

Awaiting run

Five subsystems get pushed to their limit: CPU throughput, memory bandwidth, layout engine, compositor and network path. Then the analysis engine turns the numbers into fixes.

Any URL

Now point it at a site, not just a device.

Any-URL probe

Point Redline at any public page. It fetches the document from our edge, times the origin and audits the delivery path — compression, blocking scripts, cache policy and third-party spread.

Ship it into CI

Fail the build when the page gets heavier.

Redline exposes a public audit endpoint. Post a URL and a performance budget from any CI runner — GitHub Actions, GitLab, Jenkins — and it returns HTTP 200 when the page is inside budget and 412 when it isn't, so the job fails on regressions. No account, no API key, no install.

  • minScore — the delivery grade floor
  • maxTtfbMs — time to first byte ceiling
  • maxHtmlKb — document weight ceiling
  • maxThirdParties — third-party origin cap
POST /api/public/v1/audit
curl -fsS https://redline.app/api/public/v1/audit \
  -H 'content-type: application/json' \
  -d '{
    "url": "https://your-site.com",
    "budget": {
      "minScore": 80,
      "maxTtfbMs": 600,
      "maxHtmlKb": 120,
      "maxThirdParties": 4
    }
  }'

Non-zero exit on budget breach. The JSON body lists every violation plus the full check breakdown.

How it pays for itself

Free for everyone. Priced for the teams who need the receipts.

Public
Free

Forever. Funded by ads and donations.

  • Full 5-subsystem stress test
  • Redline index + device profile
  • Baseline AI analysis
  • Runs on any browser, any device
  • Ad-supported
Run a test
Most popularTeam
$29

per month, per project

  • Saved run history & regressions
  • Deep AI analysis with cohort context
  • Test any URL, not just this page
  • Shareable reports, no ads

Cancel anytime

Enterprise
Custom

for companies with real device labs

  • CI performance budgets & gating
  • Real-device fleet aggregation
  • SSO, roles, private deployment
  • Engineer-led performance reviews
Talk to us
Billing · Public (free)

Create a Redline account to subscribe to Team. Your plan, saved runs, shareable reports and CI keys all live on your account.

Sign in to subscribe

The public tier stays free and unlimited, funded by donations and a single unobtrusive sponsor slot. Paid tiers exist for teams who need history, regressions, CI gating and fleet-wide reporting.

What's next

Tell us which device fleet you need covered.

Live now: real AI analysis of every run, run history kept on your device, and the any-URL delivery probe. Coming next: CI budgets, fleet-wide team reports, shareable public report links and a native app.

CI budgetsTeam reportsShareable reportsNative appFleet sync