lacspace-har
Analyze a browser .har export offline — waterfall, weight and waste.
npx lacspace-har session.harEverything, in one command
lacspace-har parses a HAR 1.2 export and turns it into a readable report: how many requests and bytes, where the time and weight went, how much is third-party, what came from cache, and how much compression saved (or could save). It now draws a request waterfall (ASCII in the terminal or a standalone HTML page), diffs two HARs to show what changed between before/after, gates a --budget for CI, filters requests with a query, suggests savings with rough web-vitals estimates, and can redact a HAR (strip cookies/auth/bodies) so it's safe to share. Everything runs locally — the HAR never leaves your machine. Summed phase times aren't wall-clock (requests overlap), and it's only as complete as the HAR your browser wrote.
What's inside
Totals & timing
Request count, transfer + content bytes, DOMContentLoaded/load, and aggregated timing phases.
Slowest & largest
The top requests by time and by weight, with status and type.
1st vs 3rd party
Domain breakdown split by first- and third-party origin.
Cache & compression
Cache hits, redirects, errors, and how many bytes compression saved.
Issue flags
Uncompressed text, oversized images, too many third parties, missing cache headers.
Offline & typed
Nothing uploaded; parseHar / analyzeHar / formatReport exported for your own tooling.
Waterfall (ASCII/HTML)
--waterfall draws request timing in the terminal, or -f html for a standalone page.
Diff two HARs
diff a.har b.har surfaces what got bigger, slower or newly added between two captures.
Perf budgets
--budget "js<300kb,requests<50,total<2mb" fails CI when a capture exceeds a limit.
Redact for sharing
redact strips cookies, auth headers and bodies so a HAR is safe to hand over.
Copy, paste, done
Real commands and snippets — from a one-liner to the typed library.
npx lacspace-har session.har -f html -o report.htmlA shareable page with the waterfall and breakdowns.
npx lacspace-har session.har --waterfall --width 60Request timing right in the terminal.
npx lacspace-har diff before.har after.harShows what changed in weight and timing between two captures.
npx lacspace-har session.har \
--budget "js<300kb,requests<50,total<2mb"Exits non-zero when a capture blows the budget.
npx lacspace-har redact session.har -o safe.harStrips cookies, auth and bodies.
What people build with it
✓ Triage a slow page load offline
✓ Quantify third-party weight
✓ Find uncompressed or oversized assets
✓ Turn a HAR into a shareable report
Run lacspace-har today
Free, open-source, no API keys. It's a CLI and a typed library.
npx lacspace-har session.har