JS Console — 1234.nu

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Share & Store

/p Paste /s Share /n Note (Markdown) /r Note (Rich Text) /i Image /u URL /secret Encrypted Secret /drop Local Drop /clip Clipboard Sync /hook Webhook Tester /poll Poll /survey Survey /screen Screen Share /call Video Call /board Shared Whiteboard /geoshare Live Location /my My Tools /share Share Receiver

Encode & Decode

/forge Forge /b64 Base64 / 32 / Hex /urlencode URL Encode /entities HTML Entities /escape Escape /jwt JWT /gz Gzip /zip Zip / Tar /bin Text ↔ Binary /rot ROT13 / Caesar /datauri Data URI /uni Unicode Inspector /punycode Punycode / IDN /hexdump Hex Viewer /magic Smart Decoder /charset Character Encoding /filetype File Type

Data & Config

/json JSON / YAML / TOML /jsontree JSON Tree /xml XML Studio /csv CSV ↔ JSON /xlsx Excel / XLSX /qs Query String /env .env Parser /sqllab SQL Lab /types JSON → Types /jsondiff JSON Diff /valid Validators /jtable JSON → Table /chart Chart Maker /compose Docker Compose /proxygen Proxy Config /phone Phone Parser /geojson GeoJSON Viewer /har HAR Viewer /commitlint Commit Linter /semver Semver Calculator /openapi OpenAPI / Swagger /makefile Makefile /dockerfile Dockerfile Linter /deps Vuln Scanner /jsonschema JSON Schema Validator /serialized Serialized Data

Text

/diff Diff /regex Regex Lab /case Case Converter /str String Ops /sort Sort / Filter /text Text Stats /md Markdown /post Post Formatter /slug Slugify /plain Plain Text & Invisible Characters /mdtable Markdown Table /beautify Code Formatter /lists List Comparer /htmlmd HTML → Markdown /emailhtml Email HTML Builder /jsx HTML → JSX /emailnorm Email Normalizer

Run Code

/js JS Console /py Python Console /java Java Sandbox /wasm WASM Runner

AI & Prompts

/tokens Token Counter & Visualizer /prompt Prompt Template /toolschema Tool Schema Builder /chatjson Chat Message Builder /mcpconfig MCP Config /llmstxt llms.txt /agentsmd AGENTS.md /injscan Injection Scan /abcompare A/B Compare /jsonl JSONL Viewer /mcptest MCP Tester

Agile & Scrum

/poker Planning Poker /sprint Sprint Capacity /retro Retro Formats

Crypto & Passwords

/hash Hash & Checksum /hmac HMAC /pass Password /uuid UUID / ULID /totp TOTP / 2FA Code /bip39 BIP39 Seed Phrase /pwhash Password Hash /cert Certificate Decoder /aes AES Text Encryption /age age Encryption /shamir Shamir's Secret Sharing /pwned Password Breach Check /keypair Key Pair Generator /htpasswd Basic Auth

Numbers & Math

/baseconv Base Convert /num Number Format /roman Roman Numerals /unit Unit Converter /calc Percentage Calc /prime Primes & Factors /stats Number Stats /plot Function Plotter /frac Fractions /gcd GCD & LCM /comb Combinatorics /solve Equation Solver /matrix Matrix /finance Finance /eval Math Evaluator /bit Bitwise Calculator /float Float Inspector /triangle Triangle Solver

Electronics

/ohm Ohm's Law /rescolor Resistor Colors /ledres LED Resistor /vdiv Voltage Divider /filter Filter Calculator /capcode Capacitor Code /ne555 555 Timer /rcomb Series / Parallel R-C /react Reactance /awg Wire Gauge /db Decibels /opamp Op-Amp Gain /lm317 LM317 /battery Battery Life /vdrop Voltage Drop /pcb PCB Trace Width /battpack Battery Pack /zener Zener Diode /bjt Transistor Bias /ripple PSU Ripple /fuse Fuse Selector /pwm PWM Duty /ntc Thermistor NTC /circuit Circuit Builder /kicad KiCad Viewer /serial Serial / Flasher

Radio & RF

/wavelength Wavelength /antenna Antenna Length /fspl Path Loss (FSPL) /linkbudget Link Budget /dtmf DTMF Encoder /bandplan Band Plan

IoT & Protocols

/lorawan LoRaWAN Airtime /payload Payload Size /mqtt MQTT Tree /modbus Modbus Register /mesh Meshtastic

Energy

/solar Solar Yield /batteryroi Battery ROI /tariff Tariffs /co2 Device CO₂ /evcharge EV Charging /peakload Peak Load /scop SCOP

Fabrication

/filament Filament /feeds Feeds & Speeds /lasercut Laser Cut /steps Steps/mm /stl 3D Viewer /scad SCAD /outline Photo to STL

Outdoors & Sky

/goldenhour Golden Hour /sunpos Sun Position /sunrise Sunrise / Sunset /moon Moon Phase /dewpoint Dew Point /windchill Feels Like /coords Coordinates /gpsdist GPS Distance /calories Calorie Burn /hiking Hiking Time /packing Packing List /stars Sky Map /astroplan Astro Planner /scope Telescope Setup /hunt Scavenger Hunt

Date & Time

/epoch Timestamp /tz Timezone /time Current Time /dt Date Calc /cron Cron /timer Timer / Stopwatch /snowflake ID Timestamp Decoder /datepoll Group Date Picker /workdays Business Days /eta ETA Calculator

Web & Design

/color Color /palette Palette / Contrast /gradient CSS Gradient /shadow Box Shadow /px px ↔ rem /ratio Aspect Ratio /meta Meta Tags /svg SVG Tools /favicon Favicon Maker /placeholder Placeholder Image /codeshot Code Image /cvd CVD Simulator /mermaid Mermaid Diagram /dot Graphviz DOT /font Font Inspector /bezier cubic-bezier /clamp CSS clamp() /cssjs CSS ↔ JS Object /quoteimg Quote → Image /paint Pixel Paint /meme Meme Generator /avatar Avatar Generator /pattern Pattern Generator /grid CSS Grid /glass Glassmorphism /handwrite Handwriting /illusion Optical Illusion /img2ascii Image to ASCII /blurhash BlurHash /loader CSS Loader /blob Blob & Border-Radius /robots Robots.txt Tester

Network

/x Ping /x DNS /x WHOIS /x Traceroute /x HTTP Headers /x Port Check /x Email DNS Check /x TLS / SSL Check /cidr CIDR / Subnet /ip My IP /ua User-Agent Parser /req HTTP Request Runner /mac MAC Address /secheaders Header Security /csphash CSP Hash /socket WebSocket Tester /clean URL Cleaner

Generate

/qr QR Code /lorem Lorem Ipsum /fake Fake Data /utm UTM Builder /ythumb YT Thumbnail /gitignore .gitignore /license License Text /ics Calendar Event /vcard vCard Generator /barcode Barcode Generator

Learn

/learn All explainers /learn How an LLM Works /learn How the JVM Works /learn How TypeScript Works /learn How HTTPS & TLS Work /learn How Git Works /learn How DNS Works /learn How WebRTC Works

Reference

/ascii ASCII Table /http HTTP Codes /mime MIME Types /ports Port Numbers /symbols Symbol Picker /keycode Key Event Inspector /chmod Chmod /emoji Emoji Picker /gitref Git Cheatsheet /api API & MCP /app 1234.nu Android App

Device Tests

/cam Webcam Test /mic Microphone Test /keytest Keyboard Test /mousetest Mouse Test /speaker Speaker Test /screentest Dead Pixel Test /touchtest Touchscreen Test /gamepad Gamepad Test /sensors Motion Sensors /deviceinfo Device Info /fingerprint Browser Fingerprint Self-Test /benchmark Device Benchmark /gps GPS Dashboard /lightmeter Light Meter /nfc NFC Tag

Sensors & Signals

/signal Signal Generator /lightning Lightning Distance /trigstop Trigger Stopwatch /monitor Remote Monitor /soundmeter Sound Meter /echoloc Sound Locator

Music & Audio

/tuner Instrument Tuner /metronome Metronome /notefreq Note & Frequency /delay Delay Time /capo Transpose /scales Scales & Chords /midi MIDI Inspector

Media

/img Image Convert /img Image Resize /img Image Compress /heic HEIC Converter /aud Audio Waveform /aud Audio Convert /aud Audio Trim /vid Video Convert /vid Video Compress /vid Video Trim /vid Extract Frame /vid Remove Audio /vid Change Speed /say Text to Speech /exif EXIF Viewer & Stripper /pdf PDF Tools /docmeta Document Metadata Inspector & Stripper /imgdiff Image Diff /rec Screen Recorder /ocr Image OCR /imglabel Image Labeling /stt Speech to Text /subs Subtitle Converter /imgedit Image Editor /scan QR Scanner /translate Translate /astrostack Astro Stacker /scan3d 3D Scan Capture /splat Splat Viewer

Fun

/nato Spelling Alphabet /morse Morse Code /fancy Text Styler /dice Dice Roller /banner ASCII Banner /fact Random Facts /coin Coin Flip /yesno Yes or No /asciidraw ASCII Draw /wheel Spin the Wheel /piano Piano /reaction Reaction Time /nummem Number Memory /fan Spinning Fan /fractal Fractal Explorer

Games

/play All games /play 2048 /play Minesweeper /play Word Guess /play Groups /play Snake /play Tetris /play Sudoku /play Memory Match /play Typing Test /play Connect Four /play Game of Life /play Chess /play Solitaire /play Battleship /play Breakout /play Simon /play 15 Puzzle /play Hangman /play Flappy /play Pong /play Asteroids /play Reversi /play Checkers /play Mahjong Solitaire /play Doomed /play Stunt Viper /play Voxel Strike /play Ecosystem /play Falling Sand /play Marble Roll /play Gravity /play Times Tables /play Pinball /play Sideways /play Wind-Ups /play Fluid Ink /play Horde Rush /play Neuroevolution Lab /play Bomber Arena /play 20 Questions /play Wander /play Star Battle

Dutch Tax & Money

/salaris Salary /btw BTW Calculator /box3 Box 3 /zzp ZZP Net /expat 30% Ruling /employercost Employer Cost /hypotheek Mortgage /kostenkoper Buying Costs /hra HRA /toeslagen Toeslagen /transitievergoeding Transitievergoeding /aow AOW /studieschuld Student Debt /inflatie Inflation

Money & Finance

/invest Investing /fire FIRE Calculator /split Bill Split

Health & Body

/bmi Body Metrics

← Run Code 🔒 Runs in your browser

/js — JS Console

A JavaScript and TypeScript console running in a sandboxed worker in your browser. No DOM, no cookies, no server — just code.

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Ctrl+Enter runs · variables persist across runs (reset to clear them)

TypeScript compiler (Apache-2.0) loads on demand when TS is selected (~9 MB, cached).

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