Local SQL workbench
Query CSV and Parquet files, join local tables and export results with DuckDB in your browser.
See an example →Developer
Format JSON, convert CSV, compare text and check colour contrast locally. Selected tools have protected APIs.
HAR performance viewer
Inspect local browser network logs for slow requests, timing phases and transferred bytes.
See an example →Keyboard event tester
Highlight pressed keys and inspect modifiers, repeats and a downloadable local keyboard test session.
See an example →Local MongoDB-style workbench — CamaDB
Import JSON collections, browse documents, run supported CamaDB queries, preview edits and export JSON locally.
See an example →Sprite-sheet packer
Pack small graphics into an atlas PNG and download a frame-coordinate JSON index.
See an example →IPv4 subnet calculator
Convert CIDR prefixes and netmasks, calculate address ranges and check whether an IPv4 address belongs to a subnet.
See an example →Text comparison
Find added and removed words or lines, privately in your browser.
See an example →CSV ↔ JSON converter
Convert CSV and flat JSON with headers, delimiter controls, previews and local downloads.
See an example →Colour contrast checker
Check text and background colours against WCAG AA and AAA contrast thresholds.
See an example →JSON formatter
Turn a wall of JSON into something you can read. Validate, format, and copy.
See an example →