How to automatically sort photos into categories with local AI
Classify mixed photos and screenshots by content, review the results, and download the originals grouped by category.
Read guideGUIDES
Guides
Practical guides for working with files locally in your browser and getting more from Browser Kitty tools.
How to combine a saved web page into one HTML file for offline use
Check a saved HTML page and its local resources, then package a supported static page into a single HTML file.
Read guideHow to Count Characters Without Spaces and Check Writing Length
Compare character counts with and without spaces, track a writing target, and review long sentences and repeated terms.
Read guideHow to Create an Offline Survey Form and Export Responses to CSV
Create a portable offline survey form, save responses on the device and export them to CSV.
Read guideHow to Choose the Best Photos from a Burst Without Losing Quality
Compare burst photos in groups, inspect details side by side, and save your chosen original files in a ZIP.
Read guideHow to Randomly Split a List of Names into Balanced Teams
Paste a list of names and split participants into random teams whose sizes differ by no more than one.
Read guideHow to Keep a Pomodoro Timer Visible in a Floating Window
Run a focus timer in a floating window while working in another tab or app, with options for browsers without PiP.
Read guideHow to Create a Round-Robin Schedule and Track League Standings
Generate round-robin fixtures from a participant list, enter results, and manage standings in your browser.
Read guideHow to Preview Markdown and Compare GitHub, Qiita and Zenn Styles
Write Markdown with a live preview, compare GitHub-, Qiita- and Zenn-inspired views, and save the source as .md.
Read guideHow to Add Review Comments to a PDF Without Changing the Original
Anchor review comments to PDF text or page regions, track their status and share the notes without altering the source document.
Read guideHow to Make Pixel Art Animation and Export a GIF or Sprite Sheet
Draw and animate small pixel art frame by frame, then save an animated GIF or a sprite sheet PNG.
Read guideHow to Make a Handwriting Font on Your Phone and Export TTF
Draw your own characters in a browser, preview the resulting glyphs, and save a limited-character TrueType font.
Read guideHow to Reverse a Video and Its Audio, Then Save an MP4
Reverse a short section of video or make a forward-and-back MP4, optionally reversing a compatible audio track.
Read guideHow to Create a Video Contact Sheet: Make a Thumbnail Grid from Video
Create a single image of evenly spaced video thumbnails, optionally labeled with timestamps, and save a frame-time CSV.
Read guideHow to Convert MP3 or WAV to MIDI and Correct Detected Notes
Detect notes from a short MP3 or WAV recording, correct pitches and timing, and export MIDI or a note CSV.
Read guideHow to Convert TTF/OTF to WOFF2 and Subset Japanese Web Fonts
Create WOFF2 subsets from TTF/OTF fonts and integrate the generated fonts and CSS into your website.
Read guideHow to Convert JSON to CSV and Open the Table in Excel
Turn a JSON array into a CSV table, inspect the columns, and open it in Excel without surprises.
Read guideHow to Cut Out Part of an MP3 and Join the Remaining Audio
Split an MP3 twice, remove the unwanted middle clip, check the join, and save the result as one MP3.
Read guideHow to Hear the Difference Between Equal Temperament and Just Intonation
Compare equal temperament with 5-limit just intonation using thirds and chords, inspect Hz/cents and export WAV.
Read guideHow to Remove All Speaker Notes from PowerPoint Before Sharing
Delete speaker notes in one go, either with PowerPoint's Document Inspector or locally in your browser, then verify the result.
Read guideHow to Remove Background Noise from a Voice Recording Without Uploading It
Reduce background hiss and fan noise in a voice recording, test a 10-second sample, compare both versions, and save WAV in your browser.
Read guideHow to Combine Two Photos into One Image on Your Phone
Put two photos side by side or one above the other, adjust cropping and spacing on your phone, and save them as a single JPEG or PNG.
Read guideHow to Compare Two Photos and Find Changes Even When They Are Misaligned
Align two Before/After photos to find changes, check for false differences, use a camera guide and save the result as PNG.
Read guideHow to Convert Word DOCX to Markdown (.md) and Keep Tables and Images
Convert Word DOCX to Markdown, check headings and tables, and choose between an image ZIP and a single .md file with embedded images.
Read guideHow to Convert PowerPoint to MP4 Video with Narration from Speaker Notes
Convert PowerPoint slides into a narrated MP4 using speaker notes as a script. Compare native export with the browser workflow, then prepare audio, subtitles and final video.
Read guideHow to Make Animated GIFs from Images | Frame Order, Speed and Loops
Arrange multiple images into an animation, adjust frame timing, playback direction, looping, and canvas size, then save as GIF or Animated WebP.
Read guideHow to scan paper documents to PDF on your phone, correct skew, and adjust file size
Photograph and straighten paper documents on your phone, combine pages, choose A4 and file-size targets, and check the result before submission.
Read guideHow to print queue number tickets and call the next number in your browser
For events or pickup counters where you hand out numbered tickets and call people in order, Browser Kitty's Queue Board provides a simple browser-based way to run the queue.
Read guideHow to use your phone as an auto-scrolling cue card and teleprompter
A practical way to display a script on your phone and auto-scroll it at a fixed pace or toward a target duration, with setup tips and limitations for speeches and video work.
Read guideHow to merge MP3 and WAV audio files in your browser
A practical workflow for adding several MP3, WAV, or other audio files, trimming them, arranging the final order, and exporting one combined audio file, with notes on formats, re-encoding, and browser support.
Read guideHow to use your phone as a spirit level | Check level, plumb, and slope without installing an app
A practical guide to using a phone's orientation sensor as a browser-based spirit level, including placement errors, calibration, permissions, and accuracy limits.
Read guideHow to open an ORC file in your browser | Inspect schema, statistics, and data
Understand an ORC file through its row count, compression, schema, and column statistics before inspecting records. Distinguish file-wide information from current-page sorting and CSV export.
Read guideHow to extract audio from video | Save MP4 audio as MP3, M4A, or WAV
A practical workflow for choosing one audio track from a video, saving it unchanged when supported, or converting it to MP3, M4A, or WAV, with notes on multi-audio files, large inputs, and offline use.
Read guideHow to merge multiple PDFs and add continuous page numbers | Exclude the cover and add a watermark in one workflow
Build one pipeline that merges a cover, report, and appendix, cleans up pages, splits the cover from the body, numbers only the body, merges the branches again, and applies a watermark. Save the workflow as a Recipe or Pipeline JSON for reuse.
Read guideHow to remove author information from Word, Excel, and PowerPoint before sharing
A practical workflow for inspecting author metadata, comments, speaker notes, hidden information, and other privacy-related findings in DOCX, XLSX, and PPTX before sharing.
Read guideHow to convert JPG and PNG images to PDF and combine multiple images into one file
A practical workflow for turning JPG, PNG, and WebP images into one PDF while checking page order, rotation, and page placement.
Read guideHow to fill in and hand-sign a PDF in your browser without uploading it
A practical workflow for filling supported PDF form fields, placing text and visual signatures anywhere on a page, and saving the completed PDF locally.
Read guideHow to make a video a target length by calculating playback speed and saving MP4
A practical workflow for calculating the speed needed to reach a target duration, checking audio and quality, and exporting a new MP4 without cutting the content.
Read guideHow to extract numerical data from graph images or PDFs and save it as CSV
A practical workflow for calibrating graph images or PDF pages, extracting XY coordinates manually or automatically, reviewing them, and exporting CSV.
Read guideHow to automatically detect and blur or pixelate faces in video
A practical workflow for detecting faces in video, reviewing and correcting masks, applying pixelation or blur, and creating the redacted MP4 locally.
Read guideHow to open JSONL / NDJSON files and find invalid lines
A practical workflow for inspecting line-delimited JSON, locating malformed or blank lines, and checking field presence and mixed types.
Read guideHow to open DBF files without installing software and fix garbled text
A practical workflow for opening legacy DBF data read-only, checking Japanese encodings, memo sidecar files, and deleted records.
Read guideHow to make and print planner refills at actual size
A practical workflow for creating monthly, weekly, daily, and note planner refills, exporting exact-size or A4-imposed PDFs, and printing them at 100%.
Read guideHow to add text watermarks to multiple images at once
A practical workflow for adding the same text watermark to multiple images and reusing the process together with resizing or format conversion.
Read guideHow to create a Wi-Fi QR code and share the password
A practical guide to creating a Wi-Fi connection QR code from an SSID and password, sharing it on screen, as a PNG, in print, or by copied details, and understanding the security implications of the encoded credentials.
Read guideHow to create and print label sheets at actual size
A practical workflow for defining a label sheet by real dimensions, designing one label, merging CSV / TSV data when needed, reusing partially used positions, calibrating print alignment, and generating a print-ready PDF.
Read guideHow to split a large PDF or image across A4 sheets for printing
A practical workflow for tiling a large PDF, image, or SVG across ordinary paper such as A4 while keeping the intended physical finished size explicit for printing and assembly.
Read guideHow far can FFmpeg go in the browser? Single-thread, multi-thread, and SharedArrayBuffer explained
FFmpeg can perform substantial media processing as WebAssembly in the browser, but multi-threading introduces SharedArrayBuffer and cross-origin-isolation requirements that change how the app must be delivered. This article explains why Browser Kitty's FFmpeg Filter Builder has separate ST and MT builds.
Read guideHow to run multiple PDF operations as one reusable workflow
Instead of repeating the same PDF edits manually, build page operations, branches, merges, and document finishing steps as a node pipeline, preview intermediate results, and reuse the workflow as a Recipe or Pipeline JSON.
Read guideCompare PowerPoint Files (PPTX) in Your Browser
A practical workflow for comparing an original and revised PPTX by matching slides, reviewing structured changes, and checking the rendered appearance.
Read guideWhat’s the difference between file:// and localhost? Why the same HTML can behave differently
Opening an HTML file directly with file:// and serving the same file from http://localhost are different browser environments. Origin rules, HTTP behavior, API requirements, and storage semantics can change even when the HTML is identical. This guide explains why using examples from Browser Kitty.
Read guideWhy is a PowerPoint diff harder than a text-file diff?
Text has a convenient comparison unit: lines. A PowerPoint file is instead a package of slides, shapes, text, images, layout, formatting, themes, speaker notes, and relationships between multiple parts. This article explains what building PPTX Diff taught us about presentation comparison.
Read guideWhy can browser capabilities differ even with fully local processing?
Whether processing is fully local describes where user data is processed. Whether Web NFC, WebCodecs, WebGPU, Web Share, or another feature is available depends on browser support, the operating system, hardware, permissions, and runtime conditions. This guide separates those two questions using Browser Kitty examples.
Read guideHow does Browser Kitty verify “fully local processing”?
Browser Kitty does not treat “fully local processing” as a label alone. Before using the claim, we check where user data flows, whether runtime dependencies are fetched externally, what CSP restricts, whether representative workflows create unexpected network traffic, and where explicit save/share actions hand data off.
Read guideWhy does a seed let you reproduce the same random data?
Many random-looking values are produced by deterministic pseudorandom generators. A seed chooses the generator's starting state, so the same seed can reproduce the same sequence when the same generator and processing conditions are used. This guide explains why that is useful in testing, when reproducibility breaks, and why this is different from security-grade randomness.
Read guideWhat’s the difference between local AI and cloud AI?
Local AI runs inference on the user's device, while cloud AI sends input to a server for inference. Neither is always better. This guide compares data flow, model size, latency, device load, connectivity, and how models are delivered and updated.
Read guideWhat determines video file size? Resolution, bitrate, and codecs explained
A 4K video is not automatically huge, and H.264 does not by itself determine file size. This guide starts with average bitrate and duration, then explains how resolution, frame rate, codec efficiency, and content affect quality and the bitrate you need.
Read guideWhat limits browser processing for large files?
Whether a browser can handle a large file is not determined by gigabytes alone. The practical limit depends on how much the data expands while being processed, how many buffers exist at once, how much computation is required, and whether the app can work incrementally instead of loading everything.
Read guideWhat’s the difference between CSV, JSONL, Parquet, ORC, Arrow, and Avro?
Tabular and record data can be stored or exchanged as CSV, JSONL, Parquet, ORC, Arrow, Avro, and more. These formats may hold similar data, but they optimize for different things: human readability, record-at-a-time processing, large-scale analytics, in-memory interchange, or schema-aware records.
Read guideHow can a browser process images, video, and even databases?
Modern browsers do more than display web pages. They can read files you select, manipulate image pixels, process media, and run database engines through WebAssembly. This article explains what is happening without requiring deep technical knowledge.
Read guideWhere does browser-saved data live? When it can disappear and how to think about backups
Settings and history can remain after a web app is closed without being stored in the cloud. This guide separates browser storage, exported files, and cloud storage, then explains when data can disappear and when a backup matters.
Read guideHow to open and inspect a DuckDB file in your browser
A read-only workflow for understanding a DuckDB database and inspecting only the tables, columns, and query results you need.
Read guideWhere do files go when you load them into a web tool? Local processing vs. uploads
Choosing a file does not automatically mean it is uploaded to a server. This guide explains browser-local processing, server-side uploads, hybrid designs, and the practical clues to check before using a web tool.
Read guideHow to retake a photo with nearly the same composition as an older photo
A practical workflow for retaking old photos, repeat-location records, or Before/After shots while using the reference image as an on-camera composition guide.
Read guideBenefits and caveats of saving and using single-HTML web tools
A single HTML file is easy to keep and move, but it does not automatically guarantee offline use, local-only processing, or portable app data. This guide explains the differences to check before relying on a saved copy.
Read guideHow to use your phone as a presentation remote for PPTX and PDF
A practical workflow for controlling PPTX or PDF presentations from a phone without installing a dedicated remote app or carrying a Bluetooth clicker.
Read guideHow to print text as large as possible on A4 paper
A practical workflow for fitting short notices and signs as large as possible on A4 and printing single or multi-page layouts in one job.
Read guideHow to count objects in photos while keeping track of what you counted
A practical workflow for counting dense photo contents while preserving where each item was counted, reviewing uncertain markers, and saving the results.
Read guideHow to merge, reorder, and clean up PDF pages without uploading files
A practical workflow for combining several PDFs, fixing page order, removing unwanted pages, adding images or slides, and preparing one PDF for submission or distribution.
Read guideHow to use phones as wireless sensors for synchronized vibration and impact measurement
A practical workflow for using up to four phones at once to compare how vibration and impacts differ across locations on a shared timeline.
Read guideHow to cut part of a video without re-encoding it
A practical stream-copy workflow for extracting only the needed section of a video without another generation of compression loss.
Read guideHow to extract original images from Word, Excel, and PowerPoint files
A practical way to recover embedded media directly from Office documents instead of rendering pages or taking screenshots.
Read guideHow to compress and convert images for the web without uploading them
A practical workflow for reducing image size by choosing format, quality, and resolution while visually reviewing the result.
Read guideHow to turn part of a video into a GIF or WebP animation
A practical way to extract a short video moment and turn it into a shareable GIF or WebP at an appropriate size and frame rate.
Read guideHow to build a restock list from regular items instead of rewriting your shopping list every time
A lightweight restock workflow that updates the state of regular items and automatically collects only what needs buying now.
Read guideHow to organize an overloaded to-do list by the work you can actually carry
A practical way to keep a full backlog while placing only the work you can actively carry onto a finite visual board.
Read guideHow to check your camera, microphone, and speakers before a web meeting
A short pre-meeting checklist for confirming video, audio, and browser permissions before the call starts.
Read guideHow to bundle multiple photos into one self-contained HTML album
A practical way to turn a photo folder and its viewer into one file that can be opened directly in a browser.
Read guideHow to inspect ZIP, 7z, and RAR archives before extracting them
A practical workflow for listing, previewing, and selectively extracting archive contents before unpacking everything.
Read guideHow to inspect video codecs, resolution, and audio details in your browser
A practical workflow for understanding an unfamiliar or unplayable media file before deciding whether to convert it.
Read guideHow to blur faces in photos without uploading them
A practical workflow for automatically finding faces, checking misses, and manually fixing redactions before sharing a photo.
Read guideHow to open and inspect Parquet files without installing software
A quick workflow for checking Parquet structure and sample rows when you only need to inspect the file rather than build a full data pipeline.
Read guideHow to compare PDF changes without uploading files
A practical workflow for comparing before-and-after PDFs locally and reducing the chance of missing meaningful changes.
Read guideHow to compress video in your browser without uploading it
A practical order for reducing video size while avoiding more quality loss than necessary.
Read guideHow to check and remove GPS and EXIF data before sharing photos
A checklist for reviewing hidden location and device metadata inside a photo before you share it.
Read guideHow to open and inspect a SQLite file without installing software
A read-only workflow for exploring an SQLite database from value search through record relationships, health checks, and SQL.
Read guideHow to read a QR code from a screenshot or saved image
A QR code shown on the same phone can be decoded directly from a screenshot or saved image without using another camera.
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