omikuji.dev Blog

Two timers on Omikuji Tools that do something a plain countdown does not. The Sand Timer shows the time as an hourglass, and it can now be embedded on your own page. The Multi Timer runs several timers at once and draws them as bars on a single timeline. Sand Timer Set minutes and seconds, or use a preset (1, 3, 5, 10, 15 minutes, or a 25-minute Pomodoro), and watch the grains fall. Flip behaves like a real hourglass: turn it over halfway through and the sand that has already fallen becomes the sand still to fall, so the remaining time inverts. Options: a chime when it ends, auto-flip to start again, and keep the screen awake. Space starts and pauses, R resets. The new part is Embed on your site . Pick a theme (dark or light) and a size (S 260×360, M 320×420, L 400×520), and the page gives you two lines of HTML: an <iframe> with the hourglass set to your time, and a small credit link under it. Only the embed page is allowed to be framed by other sites; everything else on ...

Picking colours for a small site tends to go in three steps. You find an image whose mood you like, you pull a few colours out of it, and then you discover that the nice mid-grey text on the nice pale background is unreadable. Omikuji Tools has a page for each step, and the colour work happens in your browser. Color Palette: colours out of an image Drop an image, paste it with Ctrl / Cmd + V, or pick a file, and the page extracts between 4 and 16 dominant colours. There are two algorithms, and the difference matters. Photo mood uses Median Cut and gives a balanced palette for the overall feel of a photo. UI / Logo uses K-Means and separates the large background areas from the small accents, which is what you want from a logo or a screenshot where the brand colour covers a few percent of the pixels. Each swatch copies as HEX, RGB or HSL, and the whole palette comes out as a Tailwind config snippet, CSS variables or a JS array. A UI preview lets you assign palette colours to backgro...

Sushi Typing is a typing game where sushi plates roll by and you type their names in romaji. It started as a ten-second sprint; it now has proper 60, 90 and 120-second courses, 76 prompts including short phrases, accuracy and speed (characters per minute), a list of the keys you miss most, and a leaderboard per course and period. The leaderboard does not trust the browser Any browser game can be "beaten" by editing the request that submits the score. So the server never receives a score. Instead: The server issues a seed for your session in a signed token. Your browser and the server generate the same sequence of prompts from that seed. You send a log of answers : which prompt, at what millisecond, what you typed. The server replays the log against its own sequence, checks every answer, and computes the score itself. On top of that it rejects anything faster than a human: under 40 ms per character, over 1,100 characters per minute overall (world-class typists reach...

Most of the video work I actually do is small: trim three clips into one with a caption, turn a screen recording into something a colleague's laptop will play, or fix an MP4 that refuses to start playing on a web page until it has fully downloaded. None of that should need a desktop editor or an upload to someone's server. Omikuji Tools has one page for each, and all three process the file inside your browser. Local Video Editor: clips, captions, background music Load videos (MP4, WebM, MOV) and audio (MP3, WAV, M4A), cut the segments you want, and line them up on a timeline — drag to reorder, click a clip to change its volume or mute it. Captions are placed at the playhead with their own start and end time, position, size and colour. Audio files go on a BGM lane with a volume control. Output is fixed at Full HD: 1920×1080 landscape or 1080×1920 portrait, at 24, 30 or 60 fps. Sources are scaled to fit with black letterboxing, so you can mix 4K footage with phone clips. The o...

The online stopwatch on Omikuji Tools fills the screen with the elapsed time, records laps, and has a few styles and colors. It has been around for a while, in 12 languages. What I did not expect was where people use it. The Chinese version took off on big screens Search impressions for the Chinese page went from 65 to 9,004 a week within six weeks, at the same ranking position. The queries that drove it were about using a timer on a large display : classrooms, events, projectors. The tool had been designed with a single person at a desk in mind. So the full-screen button, which used to be an icon only, now has a text label in every language, and the page explains how to put it on a projector. On a big screen the label is the first thing people look for. A bug the big screen made obvious While checking every language, I found that the colons and the millisecond digits were invisible in production, in all languages: the time read "00 00 00". The digits are drawn with a ...

A QR code looks like a one-step job: paste a URL, save the image. The problems show up later — the printed code is too dense to scan from across the room, the Wi-Fi code does not connect because the password had a semicolon in it, or someone hands you a code and you would like to know where it goes before your phone opens it. Omikuji Tools has three small pages for the three halves of that job, and none of them send your data anywhere. QR Code Maker The generator has tabs for a URL or plain text, Wi-Fi , a contact card (vCard) and a calendar event , plus a batch mode: paste up to 500 lines from a spreadsheet and every line becomes its own code, downloaded together as a ZIP. Single codes save as PNG or SVG. You can change the foreground and background colours, the margin and the error-correction level, and composite a logo in the centre (the page tells you to switch to level H when you do). The detail I like most is the Encoded String panel under the preview. It shows the exact te...

Two tools for the "let me just check" moments in server work. Both are free and need no sign-up. SSL Certificate Checker Type a host name and get the certificate's expiry (days remaining, colored at 30 and 7 days), issuer, subject alternative names, serial, SHA-256 fingerprint, key type, the full chain, which TLS versions (1.0 to 1.3) the server still accepts, and a verdict: expired, host name mismatch, self-signed, or incomplete chain. Ports 443, 8443, 465, 993 and 995 are supported. One honest note on architecture: the site runs on Cloudflare Workers, and Workers cannot read the peer certificate of a TLS connection. So this check is relayed to a small service on a separate machine that runs openssl s_client . The relay only accepts public host names, only those five ports, and never logs the host you typed. 👉 SSL Certificate Checker IP Address Lookup Paste an IPv4 or IPv6 address (with or without a prefix length) and get its type according to the RFC special-pu...

Mermaid is the nicest way I know to keep a diagram next to the code it describes: it is plain text, it diffs, and GitHub renders it in a README. The annoying part is everything around it — drafting a diagram somewhere you can see it, keeping more than one around, and getting an image out for a slide or a ticket. The Mermaid Editor on Omikuji Tools is a browser page for exactly that. Type on the left, see it on the right Write Mermaid code in the editor and the preview redraws as you type (it waits a moment after your last keystroke, so a half-finished line does not flicker errors at you). Flowcharts, sequence diagrams, ER diagrams, Gantt charts — whatever Mermaid itself supports. When the syntax is wrong, the preview shows Mermaid's own error message instead of a blank box. The preview behaves like a map: scroll the wheel to zoom around the cursor, double-click to zoom in, drag to pan, and one button fits the whole diagram back into view. For a wide diagram you can hide the edi...

Five new file tools on Omikuji Tools. They process files inside your browser: nothing is uploaded, and there is no queue and no size-based pricing. Tool What it does Merge PDF Combine up to 100 PDFs in any order, with page-one thumbnails Split PDF Extract, delete or split by page ranges such as 1-3, 5, 8- ; rotate pages PDF to Image PNG, JPEG or WebP at 72 to 600 dpi, one file per page or a ZIP Image to PDF Choose paper size, orientation and margins; JPEGs are embedded without re-encoding Audio Converter Convert to WAV, M4A (AAC) or WebM (Opus); trim, downmix to mono, change sample rate A few details worth knowing JPEG stays lossless. When you turn photos into a PDF, the JPEG bytes are embedded as they are. Rotation from EXIF is applied on the PDF page, so a phone photo is not re-compressed just to turn it upright. Encrypted PDFs are refused with a clear message rather than producing a broken file. Very large renders shrink gracefully. Rendering ...

The second piece of software I publish is Hakarasenai , a Firefox extension for desktop and Android. The name means "won't let it measure", and that is the entire feature list: it stops Google Analytics from measuring you. Free, MIT licensed, on addons.mozilla.org (v1.2.0). Why it exists Google ships an official "Google Analytics Opt-out Add-on", and there is a Firefox build of it. The trouble is how it works: it injects a <script> element into the page, and Firefox, like Safari, applies the page's own Content Security Policy to content scripts. On any site with a strict CSP the injection is blocked and the opt-out quietly does nothing. Nothing tells you it failed, which is the worst failure mode a privacy tool can have. I ran into this while trying to keep my own visits out of the GA4 properties of my sites, and wrote this instead. Two layers It tells the Google Analytics code on the page that you have opted out, using the same official hook...

Amidakuji is the Japanese ladder lottery: names go along the top, prizes or roles along the bottom, and each person traces a path down a ladder with random rungs. Every name lands on exactly one result, and nobody can predict it. Offices in Japan use it for seating, task assignment and drawing lots. I built a browser version that works for up to 200 people. How it works Enter names (and optionally results). Paste a column from a spreadsheet and the rows fill in automatically; tab-separated "name → result" pairs work too. Press Draw and watch each path animate down the ladder, or reveal them one at a time. Nothing is sent to a server. The whole lottery (names, results, and the random seed for the rungs) lives in the URL after the # , so you can hand the link to others and they will open exactly the same ladder. Cheat prevention : turn it on and the results stay hidden until every path has been traced. Redrawing changes the seed, so a new link means a new draw. Share...

Besides the web tools, I publish two pieces of software you install yourself. The first is Waridake ("just split it" in Japanese), a window-snapping app for macOS. Free, open source, MIT licensed. What it does (this is the whole list) You keep one layout that slices the screen into zones While dragging a window, hold Shift and the zones appear Release the mouse over a zone and the window snaps into it There is no layout editor, no hotkey grid, no window history, no Pro version. It lives in the menu bar and nothing else. It is the "this is all I need" part of the snapping apps I used before, rebuilt on its own. One JSON file for the layout The layout is ~/.config/waridake/layout.json , created on first launch. Each zone is a fraction of the screen's working area ( x , y , w , h from 0 to 1) plus a gap in points. The default is a left column split in three (25%), a wide center (50%) and a right column (25%): six zones. Zones may overlap; the first one...

This blog is where I post news about the sites I build and run under omikuji.dev . Everything is free, needs no sign-up, and wherever possible runs entirely in your browser so that nothing you type or drop into a page ever leaves your device. What is there Omikuji Tools — about 130 small web tools: timers and clocks, a ladder lottery, PDF and audio converters, text converters, network checks (SSL certificate, DNS, IP address), calculators and print templates. Most are available in 12 languages. omikuji games — 105 browser games (puzzles, logic, arcade, brain training, play against the CPU, and games for small children). Everyone gets the same daily puzzle and can post to that day's leaderboard. Japanese only for now. Reference sites — a kaomoji dictionary (59,000 Japanese text faces), an emoji dictionary, a dictionary for the Japanese word game shiritori , traditional colors of the world with sources, and a guide to etiquette mistakes travelers make abroad. These are in Ja...