Tools on TheSpielplatz
Mini-tools & experiments
Little tools, fresh from the lab.
Small things I built because I needed them. Open one, use it, close the tab. Nothing to install, nothing to sign up for.
23 tools free nothing to install
SEPA QR generator
Turn a recipient, IBAN and amount into a payment code any European banking app can scan.
Big text print
Type a word, blow it up, print it centred on A4. Size slider, display fonts, emoji included.
Polarizer
Drop in a photo, add the date and the place, download it as a polaroid.
Sample cutter
Drop an audio file in, cut the part you want, normalise it, fade the edges and download it as a WAV. Nothing is uploaded.
Email to PDF
Paste the original source of an email and print it as a clean document — subject, sender, date, body — instead of a screenshot of your inbox.
Stopwatch
Time something with laps, start it part-way in, and set alarms that go off while it runs.
Training timer
Rounds and rests with a beep at every change. Set it once, put the phone down, train.
Calendar importer
Drag an .ics file onto the page to read the event — title, time, place — then push it into Google Calendar with one click.
SVNR validator
Check an Austrian social security number against its official checksum before you file it.
Paint by numbers
Turn any picture into a printable paint-by-number sheet. Keeps a child busy for an afternoon.
Label sheets
Fill an Avery Zweckform label sheet on screen and print it so the text lands on the labels.
Cat toy
A full-screen laser dot, mouse or feather that chases the cursor. Your cat decides if it works.
Paper frame
Generates a fold-and-cut paper photo frame layout, ready to print at home.
Drone exam trainer
Practice questions for the A2 drone certificate, with the reasoning behind each answer.
Prototypes
Rough edges, still online because they still do something.
Apps
Bigger siblings with a home of their own. A couple of them want an account — lab itself never does.
- Nudge a BeatSong-request platform for DJs — guests wish and vote for songs by QR code while the DJ keeps control of Spotify playback. Login #tool
- WLED Pixel StudioDraw 2D pixel images and push them straight onto a WLED device, with a live preview while you work. #hardware #wled
- Piggy BankA read-only sats jar tied to an LNBits wallet — for the people in your life who aren't Bitcoiners yet. Login #bitcoin
Source code
Projects that live on GitHub. Read them, fork them, run them yourself.
- LNURL OIDC BridgeSign in with a Lightning wallet through any OIDC client — the wallet signs a challenge instead of sending a password. #lightning #bitcoin
- Backup Card CreatorTurns a BIP39 mnemonic into a printable backup card, cover sheet, zpub and address list. #bitcoin
- FreezerA live Linux system that loads entirely into RAM, so you can pull the USB stick and nothing is ever written to disk. #bitcoin
- Phase ControlAn ESP32 bolted onto a phase-control board so the whole thing can be driven from a web interface. #esp32 #hardware
- FOSS ToolsA free and open source collection of the small tools from my daily work life, rewritten so they do what I actually need. #foss