Free tools that run in your browser
Clean, convert and check CSV, JSON, text, schedules and configuration. Every tool runs on your device, so the files and text you use stay there.
- Free, no account
- Runs in your browser
- Files are not uploaded
Data & CSV
Clean, profile, validate, convert, merge and compare CSV, JSON and plain text. CSV cells are never turned into numbers, so identifiers such as 00123 keep their leading zeros.
Clean a CSV online
Trim spaces and remove exact duplicate rows.Convert CSV to JSON
Turn CSV rows into JSON objects, with every cell kept as text.Convert JSON to CSV
Turn a flat JSON array into a spreadsheet-safe CSV.Compare two texts (diff)
See every added and removed line between two versions of a text.Merge CSV files
Stack 2 to 20 CSV files with the same header into one CSV.Compare two JSON datasets by key
Match records by key and list additions, removals and changes.Validate a CSV file
Check each CSV column against rules: type, required, unique, range and allowed values.Profile a CSV file
Count blanks, duplicates, leading zeros and lengths in every column.Product catalog checker
Check a product CSV for blank titles, duplicate SKUs, prices and allowed currencies.
Developer
Check JSON, cron schedules, configuration drift, event telemetry, dependency licenses, release evidence and source freshness before you ship. Each check gives a report; nothing is fetched, scheduled or applied.
Check JSON against a schema
Validate JSON against a schema and see the path of every problem.Preview a cron schedule
See every run of a cron schedule, including clock changes.Compare configuration drift
Compare two JSON configurations, with risk labels and masked secrets.Lint an event telemetry schema
Check an analytics event dictionary for privacy and contract problems.Inventory dependencies and licenses
List every dependency and version, and check licenses against your policy.Check source freshness
Find stale or unknown sources and the claims that rely on them.Check release readiness
Turn release evidence into a gate checklist; missing evidence stays missing.
Everyday
Convert and check subtitles, draw random teams, plan cuts and room layouts, check USB-C chargers, estimate battery runtime, power station energy and appliance running costs. The same input always gives the same result.
Convert SRT to WebVTT
Convert SRT subtitles to WebVTT and flag overlapping cues.Random team generator
Split names into random teams for several rounds, reproducibly from a seed.Battery runtime calculator
Estimate how long a battery runs a load, with every step shown.USB-C charger compatibility check
Will this USB-C charger, cable and device work together? Compare their declared specs.Power station energy planner
Check whether a power station or solar battery covers your devices, and for how long.Room layout planner
Plan where furniture fits in a room, with doors, obstacles and walking clearance.Appliance energy cost calculator
Work out what your appliances cost to run per day, month or year, from watts and hours.Cut list calculator
Plan how to cut boards or sheets into pieces, with saw kerf and a layout diagram.Check subtitle timing and reading speed
Find subtitle cues that are too fast, too long or overlapping.
Private by design
Every tool in this release runs as deterministic JavaScript on your device. Useful Commons does not receive the text or files you process. See Privacy for the details.