27 tools · no account · no upload
The practical toolkit that stays in your browser
Merge PDFs, edit audio, record, compare time and calculate without installing an app. Your files stay on this device.
Tools
Quick starts
- PDF
Merge PDF
Combine two or more PDF files in the order you choose.
- Images
Image compressor
Compress still JPEG, PNG and WebP images locally by quality or a best-effort target size.
- Audio
Voice recorder
Record microphone audio, pause when needed and download the result.
- Video
Screen recorder
Record a desktop screen or browser tab, with optional microphone narration.
- Date and time
Stopwatch
Measure elapsed time, record laps and splits, and export the results as CSV.
- Calculators
Grade calculator
Calculate a weighted grade and the score needed on a final exam.
- PDF
PDF pages per sheet
Arrange several PDF pages on each output sheet for compact printing.
- Audio
Audio cutter
Keep or remove an audio selection, with fades and a ringtone preset.
- Date and time
Timer
Set a countdown with quick presets and an alert when time runs out.
- Calculators
GPA calculator
Calculate a credit-weighted GPA from letter grades or grade points.
- PDF
PDF to grayscale
Convert PDF pages to grayscale with a selectable output resolution.
- Audio
Audio merge
Join audio tracks in order and add optional fades or crossfades.
- Date and time
Date format converter
Show one date in common regional, compact, ordinal and Unix formats.
- Calculators
Cooking converter
Convert cooking volumes, ingredient weights and temperatures.
- PDF
PDF to text
Extract embedded text from PDF pages into a plain text file.
- Audio
Audio speed
Speed up or slow down an audio file while preserving its pitch.
- Date and time
Age calculator
Calculate age on a chosen date and see the time until the next birthday.
- Calculators
Tournament calculator
Explore Swiss structures, records and modeled qualification chances for supported card games.
- PDF
Straighten PDF scan
Straighten scanned PDF pages automatically or with a manual angle.
- Date and time
Time duration
Find the duration between two clock times, including spans across midnight.
- Calculators
Random number generator
Generate one or more integers within a range, with optional uniqueness and sorting.
- PDF
Sign PDF
Draw or import a visual signature and place it on one or more PDF pages.
- Date and time
Quarter finder
Find the calendar quarter, half-year and quarter boundaries for any date.
- Calculators
Pace calculator
Calculate running pace, speed, finish time or distance with kilometre and mile units.
- Date and time
Timestamp converter
Convert Unix timestamps and ISO dates in single or batch mode.
- Date and time
Time zone difference
Compare two time zones for a chosen local date and time.
- Date and time
Sleep calculator
Explore suggested bedtimes or wake-up times based on approximate sleep cycles.
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The boundary
Local by design
Browser processing
Selected file bytes stay in the browser while a tool runs.
No account
Open a tool and start. There is no sign-up step.
Clear limits
Accepted formats and working limits are shown before processing.
Blog
Field guides
Lutrakit is now available in French
See what is translated, how French URLs work and which browser-local privacy guarantees remain unchanged.
Pace, speed and finish time without unit mistakes
Convert running pace, speed and finish time with exact mile and kilometre units, worked examples, rounding checks and honest limits.
What a browser screen recorder can capture
Choose between a browser tab, an application window, and an entire display while limiting accidental exposure.