Doing the job
One per tool: what the job involves, which setting matters, and what it costs you.
- How to Compress an Image Under a File-Size Limit An upload form wants 500 KB and your photo is 4 MB. What a size limit really costs, which setting to move first, and why a PNG will not shrink the way a JPEG does.
- How to resize an image without wrecking it What changes when you resize: fine detail lost when shrinking, interpolation when enlarging, fitting a different shape, and choosing when to crop.
- How to arrange multiple images into one picture Make a collage, contact sheet or image strip: choose a grid, keep pictures whole or crop to fill, set the spacing and save a PNG, JPEG or WebP without uploading.
- How to take a passport photo that is not sent back What a passport photo is actually measured on - head height, eye line, background - which country wants which numbers, and how to hit the pixel and KB limits an online form enforces.
- How to make a favicon that still reads at sixteen pixels Which sizes a favicon.ico actually needs, which extra files iPhones, Android and a Mac ask for, and why a logo that works on a poster disappears at sixteen pixels.
- How to convert an SVG to a PNG at the right size A vector has no pixel size of its own, so the number is yours to choose. Where that number comes from for a screen, an app icon and a printer, and what changes when a drawing becomes pixels.
- When to put a picture inside your CSS, and when not to What a data URI costs, why base64 adds a third and gzip does not give it back, why an SVG should never be base64, and the quoting mistake that breaks inlined SVGs silently.
- What a photo says about you, and how to take it out A photo off a phone usually carries the exact spot it was taken, the time to the second, and the camera's serial number. What is in there, who can read it, and how to take it out without touching the picture.
- How to redact an image so the hidden part is really gone Black boxes drawn in most programs sit on top of the picture and can be moved aside. What separates a real redaction from a covered one, why pixelated text can be read back, and how to check a file before you send it.
- How to stack photographs to reduce noise, or remove people Stacking combines a burst of frames into one picture. Which method to use depends on what you are trying to lose: noise, passers-by, or the shallow depth of field on a macro shot. How each one works, what it costs, and how RAW files fit in.
- How to open a DCM file, and what is in one What a .dcm file is and what opens one, what is on a hospital disc, why the files have no extension, how to open a DCM file in a browser, what window and level actually does, and what a scan carries about the patient besides the picture.
- The photo your phone saved, and the format nothing will open iPhones save photos as HEIC, and half the internet cannot open one. What the format is, why only Safari decodes it, what converting costs the picture, and how to do it without uploading the photos to anyone.
- The picture the web saved, and the format everything still takes Saved a picture from a website and got a .webp nothing will open? What WebP is, why converting makes the file larger rather than smaller, what happens to transparency, and how to do it without uploading anything.
- The same picture, a third smaller, with the transparency intact WebP is smaller than PNG even without losing anything - and far smaller if you let it. Which of the two you want depends on what is in the picture. What each mode does, what it saves, and how to convert without uploading.
- The file nothing will open, except the thing you are reading this in Downloaded a picture and got a .avif that no program will open? Your browser reads it perfectly, which is why converting needs no upload. What AVIF is, what a JPEG cannot carry over, and why the JPG comes out several times larger.
- How to merge, split and reorder PDF pages Combine PDFs, cut one into several, and move pages around: what survives the reshuffle, what no tool can carry across, and why none of it needs uploading your documents anywhere.
- How to unlock a PDF, and which kind of locked it is A PDF that will not print and a PDF that will not open are two different problems with one name. What each of them actually is, why one comes off in a click and the other cannot come off at all, and how to tell which you have.
- How to password-protect a PDF, and what it is actually worth A password on a PDF is a real lock. A restriction on printing is a request. What each one does, which encryption to choose, why the upload is the strange part of every online tool, and what happens if you forget the password.
- How to watermark a PDF, and what the stamp is actually for Why lenders and landlords ask for a scan to be stamped with their name, what the stamp does and does not prevent, how to do it in your browser without uploading the document, and what to write on it.
- How to redact a PDF so the text is really gone A black box drawn in a PDF reader usually leaves the words underneath it, and copy-and-paste gets them straight back. What a real redaction removes, the four places a word hides outside the page, and how to check a file before you send it.
- How to make a PDF smaller, and why some will not shrink Where a PDF's size actually is, why a scan compresses 80% and a contract barely moves, what DPI means here, and what a compressor should never do to your document.
- How to check a bank statement CSV before you trust it Check a converted bank statement CSV for wrong amounts, missing rows and misread dates. A worked example shows what running balances can and cannot prove.
- How to combine images into one PDF Turn photos or scans into a single PDF: page size, order and rotation, why a JPEG need not lose any quality on the way in, and what a PDF tells the person you send it to.
- How to scan a document with your phone What separates a photograph of a page from a scan of one: the angle, the uneven light, and the file size. How to take the photo, what to fix afterwards, and why none of it needs a server.
- Extract receipt and invoice details from photos How to check receipt OCR and crops, choose one email currency and manual or historical rates, then email compressed images with each converted value, the document count and a grand total.
- How to turn a folder of images into a video Make an MP4 slideshow from photos: what frame rate and duration actually control, how to handle pictures that are the wrong shape, and why the result has no soundtrack.
- How to make an animated GIF from images Turn a set of pictures into one animated GIF: how fast a GIF can really play, what the palette setting changes, and the three things that actually make the file smaller.
- How to trim a video without re-encoding it Cutting a clip need not lose a single byte of quality. Why a cut sometimes lands earlier than you marked it, what a keyframe has to do with it, and when to accept a re-encode.
- How to compress a video to a size that will send What a size limit actually costs a video, where the megabytes go, why the frame size drops before the picture goes to mud, how to lose as little as the number allows, and how to do it in your browser without the upload.
- How to convert a video to the MP4 that uploads What an MP4 that uploads actually is, why a WebM, an MKV or an iPhone MOV gets refused, which conversions lose nothing and which cost a generation, and how to do it in your browser without uploading the file.
- How to rotate a video without losing quality Why a phone clip plays sideways, what the nine numbers in its header do, why most rotators re-encode for nothing, when to bake the turn in instead, and how to turn a video in your browser without uploading it.
- How to crop a video to a different shape Cut a clip down to a square, a 9:16 portrait, or an exact pixel box. Which ratio each platform wants, why cropping has to re-encode when trimming does not, and what that costs.
- How to reverse a video Play a clip backwards: what reversing does to the picture and the sound, why it cannot be done without re-encoding, why it is slower than trimming, and what to do first.
- How to save a frame from a video as a picture Get a still out of a clip at its real resolution: why a screenshot of a paused player is not the same picture, which format to save it in, and how to land on the exact frame you meant.
- How to extract the sound from a video Extract a video soundtrack locally as WAV. Choose PCM16 or Float32, keep the channels or mix to mono, and check the result before saving.
- How to trim audio without losing quality Where an audio cut actually lands, why it can be exact when a video cut cannot, why a join sometimes clicks, and what a five-millisecond fade is really doing.
- How to make a QR code that still scans on somebody else's phone Which error-correction level to pick, why the white margin around a QR code is part of the code, how big to print it, and what a free generator's 'dynamic' code costs you later.
- How to check a download against its checksum How to check an MD5 or SHA-256 checksum on Windows, macOS and Linux or in your browser, what a match actually proves, and the mistake that makes the whole exercise pointless.
- How to turn a video into a GIF Which section, which width and which frame rate to choose, why a GIF of a video is ten times the size of the video, and when to use one at all.
- How to convert a GIF to MP4, and why it gets so much smaller Why an MP4 of the same animation is a tenth of the size of the GIF, what a video cannot do that a GIF can, why the frame timing is what most converters get wrong, and how to convert a GIF in your browser without uploading it.
- How to split a GIF into frames Get every frame of an animated GIF as a PNG: why some frames are only a small patch of the picture, what happens to the transparency, and how to keep the timing so you can put it back together.
- What is actually inside a GIF Frames, delays, disposal methods and colour tables explained, why browsers refuse the fastest delays, and how to work out where a GIF's file size really went.
- How to convert between YAML and JSON Convert a supported YAML subset to JSON, or JSON to YAML, in your browser. Check comment loss, unsupported constructs and exact number text before reuse.
- How to format and check XML Format, minify and check XML locally. Follow parser errors and understand the attribute, text and array mapping before converting XML to JSON.
- How to format JSON without handing it to anybody How to lay out, check and minify JSON in your own browser - what a formatter must never change about your file, how to read the error message, and why the site you paste it into matters.
- How to share text and files between devices without uploading them Move text or files from one browser to another over a direct encrypted connection - no email-to-self, no chat history, no account, and nothing stored on any server to delete later.
- How to watch a camera from another device Reuse a phone for nursery checks, pets, entryways or DIY inspections. Connect two browsers on a reachable home network and approve the live viewer.
- How to make a height comparison chart Turn a list of heights into a side-by-side picture: how to write the heights, which figure to pick for a child, why one familiar object does more than a third person, and how to get the chart out as a PNG or an SVG.
- How to trace an image into an SVG Turn a logo, a stencil, a signature or a silhouette into a real vector outline in your browser. Which pictures trace well, which never will, and how to fix the parts the tracer gets wrong.
- How to preview a Google Business Profile before it goes live What your Google listing will look like on a desktop search, on a phone and in the local pack: how long a name survives, why the category does more work than the description, which fields turn into buttons, and what the Open or Closed line says when nobody is watching.
Chaining the tools
Jobs that take two or three tools in a row - which order to run them in, and why the order matters.
- How to make a GIF from part of a video Cut the seconds that matter first, then convert only those. When the GIF converter's own timeline is enough, when to cut with the video cutter instead, and why every second of GIF costs so much.
- How to make a boomerang video Cut the moment, reverse the copy, join the two, and loop it. Three tools in a row, all running in your browser, and the order that keeps the whole job down to a minute.
- How to turn a long video into a timelapse An hour of footage into a watchable minute: how to choose the speed, why saying the finished length beats doing arithmetic, and when the result should become a GIF.
- How to make a video thumbnail from the exact right frame Step to the precise frame, save it losslessly, size it for the platform, and hit the byte limit. Three browser tools in a row, and the footage never leaves your machine.
- How to edit a GIF frame by frame Take a GIF apart into its frames, drop or reorder them, and rebuild it with the timing kept. What survives the round trip, what the palette costs, and how to see why a GIF is heavy.
- How to scan multiple pages into one small PDF Photograph every page, get one PDF, combine it with documents you already have, and shrink it until it sends. Three browser tools in a row, and the paperwork never leaves your phone.
- How to get phone photos ready for the web HEIC to JPEG, GPS stripped, resized for the page and compressed to a budget - the whole pipeline in the browser, and the originals never leave your machine.
- How to make a QR code and prove it scans Generate the code, then verify it with a reader on the same site - the exact payload, the real link, at print size and from a photo - before the print run. All in the browser, nothing uploaded.
- How to clean up a voice memo before sending it Cut the dead air and the false starts, then bring the level up to full scale. Two browser tools in a row, in the order that keeps the quality, and the recording never leaves your machine.
- How to compare two JSON files Format both files the same way, sort the keys, then diff them. Why a raw JSON diff is mostly noise, how to canonicalise both sides in the browser, and what survives to the patch.
Before you upload anything
What handing a file to a website actually does, and how to tell whether it had to happen.
- Is it safe to upload files to online converters? Most online converters send your file to a server. What that means, what happens to it there, and four checks that tell you whether a tool needs to.
- What 20 online converters do with your file We sent the same file to 20 free online converters and watched the network. 19 uploaded it. Which ones, where to, how soon, and what their privacy policies promise.
- Is it safe to scan a QR code? Scanning a QR code is reading, not opening - the danger starts one tap later. What a code actually contains, how the sticker scam works, and the three ways an address lies.
- Is it safe to upload a photo of your ID? An identity document is the one file where “probably fine” is not good enough. What an ID leak actually costs, why the risky moment is the resize before the application, and how to do all of it without the document leaving your machine.
- Is it safe to upload a bank statement? A statement is every payee, every amount and your balance in one file. Here is what a converter receives, what the careful ones do with it, and how to tell whether the upload needed to happen at all.
- Can blacked-out text be recovered? Often, yes - because most black boxes are drawn over the text rather than put in its place. The three ways redaction fails, the copies a file keeps of its own past, and how to remove something so it stays removed.
- Is it safe to paste text into an online tool? Pasting feels like moving text between your own windows, and for many web tools it is a quiet upload instead. What pasted text can carry, where it goes, and how to tell whether a formatter keeps it.
- Is it safe to use an online password generator? The right suspicion, examined: where a browser's randomness comes from, what a generator page could do wrong, and the checks that tell you whether the one in front of you can keep what it made.
- Is base64 encryption? No - and the difference matters in practice. Encoding, encryption and hashing solve three different problems: one anybody can reverse, one the key holder can reverse, one nobody can. Which is which, and how to tell on sight.
- What a PDF remembers Author names, the Word file it used to be, comments, attachments - and sometimes every earlier version of itself, deletions included. Where a PDF keeps its memory, and how to send one without its history.
- Does converting a photo remove its metadata? Sometimes - and both outcomes surprise people. Which operations strip EXIF, which quietly keep it, why the screen shows no difference either way, and how to check a file instead of assuming.
- How can a web page work with the wi-fi off? How a service worker caches browser tools, what an offline operation proves about local processing, and the network features and limits to check.
- What's inside a DICOM file? A medical scan is a patient record with a picture inside: name, birth date, hospital numbers, the institution, and keys back into the archive. What the header carries, why deleting the name is not anonymising, and how to look without uploading.
- Can an AI agent use these tools? An agent can operate these browser tools. Check browser location, the agent vendor’s data handling, required permissions and any deliberate network feature.
- Is it safe to upload files to an AI? A chat window is an upload form that does not look like one. Where a file you hand to an AI actually goes, how that differs from a converter, and how to send less - and send it clean - when the job is worth it.
Every guide here describes a tool that runs on your own machine: see all of them.