Mozhi · மொழி · Tamil voice typing
Mozhi is an open-source desktop app I designed and built for Tamil speakers. Double-tap Control, speak Tamil, Tanglish or English, and it types into whatever app you're in: Slack, WhatsApp, Gmail, Notes, VS Code. Whisper runs on your own computer, so your voice never leaves it.
Contents
Seven chapters, from one line in a README to a third version anyone can install. Read it the way it happened, or jump straight to a part.
Sparkபொறி
One sentence in the README set the whole brief, and every decision after it had to answer to all four of its parts.
Spark · The brief
Tamil speakers, writing by voice, in Tamil, on their own machines. Each phrase rules something out: an English-first dictation tool, a cloud service, an account, a subscription.
From the README
Tamil speakers should be able to write by voice in their own language, on their own computer.
No account. No cloud. No telemetry. Free, Apache-2.0, and அன்னைத் தமிழுக்கு, for Mother Tamil.
Spark · How Tamil is written
On WhatsApp, Tamil is often typed in Latin letters. At work it slides into English halfway through a sentence. Mozhi treats all of it as real writing, not as mistakes to correct.
Tanglish is a writing mode
“Tamil, in the Latin letters you already type on WhatsApp.” Mozhi's transliteration follows chat habits, zh for ழ, tr for ற்ற, long vowels doubled, instead of an academic standard nobody types.
Naalaikku meeting-a pathu manikku vechukkalaamaa?
The register is spoken
The interface is written the way people talk. The contributor guide says it plainly: use the word people say aloud, not a formal coinage.
Problemசிக்கல்
Three things break Tamil dictation: English inside Tamil, words the model invents, and text pasted somewhere it doesn't belong.
Problem · Two languages, one line
Say this to a speech model and it can go wrong two ways: meeting comes back as மீட்டிங், or the whole line is heard as English. Both are wrong for someone who said it in Tamil.
நாளைக்கு meeting-அ பத்து மணிக்கு வெச்சுக்கலாமா?
“Shall we keep tomorrow's meeting at ten?”
Problem · Words nobody said
Whisper learned from YouTube subtitles, so in silence it sometimes types a sign-off nobody said. Mozhi trims the silence first with a voice detector, “the single best defence” in the code's own words, then strips the phrases it knows Whisper invents, in English and in Tamil.
Problem · The wrong window
A dictation tool types into other people's apps. One message pasted into the wrong chat and nobody trusts it again. That line from the contributor guide became four rules.
Before anything is pasted, the pill says where it's going: இதில் எழுதும் Typing into Slack › Message #general. Switch apps mid-sentence and it follows you.
The pill is a non-activating panel. Your app keeps the cursor the whole time, so the text lands exactly where you left it.
It never records your typing. The key hook watches for the double-tap, plus Enter and Esc only while the pill is open.
Mozhi snapshots your clipboard, pastes, and puts it back 350 ms later, unless something else wrote to it meanwhile.
Systemஅமைப்பு
A Rust core, two small web views and Whisper, all on the same computer as your voice.
System · The dictation loop
Tauri 2 with a Rust core runs the state machine, the microphone, the models and the paste. The pill and the settings are plain TypeScript. Nothing in the loop needs the internet.
⌃⌃ Remember the app and field you're in
System · The double-tap
Control is the key you hold for everything else, so Ctrl+C must never start Mozhi. A tap is a press and release of the trigger on its own, under 260 ms, and the second must come within 380 ms. Try it.
Tap control on your keyboard twice, or tap this key.
Waiting for two taps
System · Eight models
From a 60 MB base to a 1.6 GB full-precision turbo, including two Tamil fine-tunes. Since v0.2.0 Mozhi starts with Tamil Small, a Whisper fine-tune from IIT Madras SPRING Lab. Only one model stays in memory at a time, and every download is checked against its SHA-256.
Tamil only
Tamil only
English, in practice
The trade-off is real: the Tamil fine-tunes are the most accurate for Tamil, but they write English words in Tamil script. Bring your own: drop a ggml .bin into the models folder and it appears in the list.
System · Polish, guarded
Polish is off by default. Switch it on and a small model on your machine, through Ollama, tidies punctuation and keeps English words in English. Its prompt opens with “You are a dictation clean-up filter, not an assistant.” And when it misbehaves, Mozhi throws its answer away.
An answer is also thrown out if it is shorter than half or longer than 1.6 times what you said. If polish takes more than 6 s, or Ollama isn't running, the raw transcript is pasted instead. The answers above are illustrative; the rules are the ones in the code.
Designவடிவமைப்பு
One floating pill, seven marks that move with your voice, and a settings app that speaks Tamil first.
Design · The pill
It floats at the bottom of the screen, above whatever you're writing in, and never steals the cursor. This is the real component, running here: the same markup, the same voice indicator, the same Tamil.
Design · Three dots that listen
The logo's three dots are the voice indicator. Seven marks morph between five states, and any state can interrupt any other because every mark eases toward its target each frame. Pick a state.
தயார்ready, double-tap ⌃⌃
With reduced motion the marks hold still and the colour and label carry the state.
Design · Three ways to write
You say one sentence. Mozhi writes it in Tamil script, in Tanglish or in English. Auto, the default, picks Tamil or English for each sentence.
You say“நாளைக்கு meeting-அ பத்து மணிக்கு வெச்சுக்கலாமா?”
whisper language: tawhisper language: ta → chat-style transliterationwhisper language: enDesign · Tamil leads
The settings app opens in Tamil, with every heading in Tamil and its English beside it. Models are postage stamps with speed and Tamil-accuracy meters. History is a stack of palm-leaf receipts that never leaves your computer.
Onboarding opens with வணக்கம்! and takes four steps: hello, permissions, a model download, and a first try. Error messages say what happened and where, Slack-இல் ஒட்டப்பட்டது, never a vague “something went wrong”.
Brandஅடையாளம்
“Every word starts as a dot.” The brand book opens with that line, and everything else is drawn from Tamil Nadu, around 1000 CE.
Brand · ஃ, the mark
Āytham is three dots in a triangle. It became the logo, the app icon and the voice indicator, and it means three things at once.
Āythamஆய்தம்A letter no other script has, with a sound of its own.
The Muvendarமூவேந்தர்Chera, Chola and Pandya, the three crowned kings who carried Tamil for two thousand years.
Every kolam starts as a grid of dots on the doorstep at dawn.
Brand · Colour
Every colour has a Tamil name for something real. “Red is the ground, turmeric is the voice, palm-leaf cream is where text is read.” Tap a swatch to copy it.
Brand · Type
The wordmark is Anek Tamil at its heaviest and narrowest, “condensed like a Manjapai print”, the cloth shopping bag every Tamil home has. One letter gets the turmeric: ழ, the sound only Tamil has.
மொழி
Brand · Motifs
The patterns aren't stock. A small Python script generates every one as SVG, the same output every time: a sikku kolam traced as one unbroken line, the Thanjavur temple on a pixel grid, and the ring of fire around Nataraja.
Shipவெளியீடு
A landing page that reads Tamil first, a privacy policy you can read in ten seconds, and a beta for two operating systems, in public.
Ship · The site
Every heading is Tamil first with English underneath, from பேசுங்க. எழுத்தாகும். down to a bilingual FAQ. Scroll the page inside the window, or open it.
Ship · A privacy receipt
“Privacy is the product,” says the contributor guide. So the promise is printed like a copper-plate charter, செப்பேடு No. 1010, with every line you'd want to check and a total of ₹0.
Ship · Launch day
The public history covers one day. Most of the app was built before it starts: it landed as a single commit of 116 files. What the day shows is the release, mistakes included.
3b4ededf1eb674f7954e44d6030ab5e717482190a564ee1d9f866fdcb54bbeb6824cb833a193ed846a98Ship · The betas
Beta 1 shipped at 13:39. The installers are tiny because the speech models aren't inside them; you choose one after install. They aren't signed yet, and the site says so instead of hoping you won't notice. v0.2.0 was tagged the same afternoon.
.dmgmacOS 12+, Apple Silicon. Ad-hoc signed, not notarised: right-click, then Open.-setup.exeWindows 10 and 11, x64. Not code-signed: More info, then Run anyway..msiWindows 10 and 11, x64, for managed installs.tagged 14:44Edit in the pill: click the text to stop and fix it, Enter pastes. Tamil Small becomes the default model.Ship · Version three
v0.3.0 shipped on 1 November, three days after Beta 1. Two of its three changes remove a moment where you had to start over: stopping to fix a word, and losing a recording to an error. v0.3.1 followed the same day with two fixes.
Edit while you speak
Click into the text while Mozhi is still listening. Fix a name, add a line: every phrase you say next goes in where your cursor is, and the words it is still hearing show on a live line underneath. ↵ inserts, ⇧↵ adds a line, esc cancels.
Emoji, without leaving the pill
A 😊 button opens a picker with an everyday row, your recent picks and every emoji by group. Search in English, Tamil or Tanglish: heart, இதயம், sirippu, sapadu, vanakkam. Or just say it: “heart emoji”, “இதயம் எமோஜி”.
Errors that keep your words
If a transcription fails, the recording is kept. Try again shows the new result for you to check before it goes in, Copy text saves what you have, and Report opens a GitHub issue with your version and the error, never anything you dictated.
v0.3.1two fixes, same day
இப்போதே பெறுங்கள்Get v0.3.1:Mac (.dmg)Windows (.exe)Release notes
Reflectionசிந்தனை
One sentence of brief, a tool that keeps your voice at home, and a small offering to the language I think in.
Reflection · Results
Speak Tamil, Tanglish or English. It types, on your own computer.
Reflection · Lessons
Most of the hard parts weren't the model. They were respect: for how people talk, where their text goes and who hears them.
Tanglish and English words are part of Tamil today. Treating them as errors would have made a tool for nobody.
Name the target, never take focus, give the clipboard back. Four small rules carry more weight than accuracy.
Trim the silence, strip the invented lines, and let polish fail back to the raw words instead of improvising.
ஃ, the kolam and the temple came from the language itself, generated by a script, not borrowed from a stock set.
“Coming soon” until the beta was real, unsigned builds labelled as unsigned, and a failed build fixed in the open.
Reflection · What's next
Straight from the site's call for contributors. Nothing here is promised by a date.
Reflection
அன்னைத் தமிழுக்கு ஒரு சிறு காணிக்கை. A small offering to Mother Tamil.
Mozhi is free, open source and has no account and no cloud. It exists so that Tamil can be spoken to a computer and written back without leaving the room it was spoken in.
Tamil belongs to everyone who speaks it, and so does this tool. Fork it, fix it, teach it your district's way of talking.
அகர முதல எழுத்தெல்லாம் ஆதி
பகவன் முதற்றே உலகு