Tamil Bridge — தமிழ் பாலம்
Learn English and Hindi through Tamil. Voice teaching, sentence explanation,
photo translation, any-language translation, dictionary, phonics, and the
complete alphabet of all three languages.
Zero cost, permanently. No API keys, no subscriptions, no server required.
Moving to a new computer, or picking this up after a long gap?
Read HANDOVER.md — what to install, where every account
lives, how to make a change and put it live, and what to do if a service
disappears.
How to run — easiest first
1. Double-click (no install, nothing to set up)
Open index.html. That's it. The whole app runs in the browser.
2. One click, with a local server
Double-click Start Tamil Bridge.bat (Windows) or run ./start.sh
(Mac/Linux). It starts a local server on http://localhost:5177 and opens it.
A server is slightly better than file:// because the browser gives it a
stable origin, so your sign-in and history survive reliably.
3. Put it on the web (free forever)
See Deploying below.
What it does
| Feature | Notes |
|---|
| Translate | Any language → any language, translating as you type, like Google Translate. Auto-detect, swap, speaker on both sides, tap any word for its meaning. |
| Romanised typing | Type vanakkam → வணக்கம், namaste → नमस्ते. Dictionary-backed, so common words come out exactly right. |
| Meaning | cat → பூனை (pūṉai) / बिल्ली. Works from any language, and from romanised input (poonai). Part of speech, IPA, examples, synonyms, related words. |
| Sentence Explainer | Word-by-word gloss, part of speech, tense with its formula, subject/verb/object, and the SOV↔SVO word-order shift — explained in Tamil. |
| Spelling & grammar check | Targets the mistakes Tamil speakers actually make: missing articles, -s agreement, did went, a/an, plurals after numbers. |
| Voice teaching | The browser's own speech engine narrates lessons in Tamil and reads the target language slowly. Free, offline, no key. |
| Pronunciation practice | Speak into the mic, get a score per word with Tamil feedback. |
| Photo translate | OCR from a photo in 23 scripts (Tesseract.js), then translate. |
| Alphabet | Tamil all 247 (12 உயிர் + 18 மெய் + ஃ + 216 உயிர்மெய்), Hindi full varnamala + barakhadi, English A–Z with sounds. |
| Phonics | All 44 English phonemes with Tamil articulation notes, flagging the sounds Tamil does not have (/θ/ /f/ /v/ /z/ /æ/). |
| Vocabulary | 201 words across 19 themes, each in Tamil / English / Hindi with romanisation, IPA, and the sound written in Tamil letters. |
| Lessons | 10 graded units, 60 aligned sentences, grammar notes and quizzes. |
| Practice | Spaced repetition (SM-2), four directions, streaks and XP. |
| Accounts & history | Email or phone sign-in, every action logged, searchable, exportable. |
| Interface language | Tamil or English — the EN / த button in the top bar. |
Is it really free?
Yes, and here is exactly why — so you can verify it.
| Part | What it uses | Cost |
|---|
| Voice (speak + listen) | Web Speech API, built into Chrome/Edge | free, no key |
| Translation | Google gtx endpoint → MyMemory → LibreTranslate → offline dictionary | free, no key |
| English definitions | dictionaryapi.dev | free, no key |
| Photo OCR | Tesseract.js (Apache-2.0) from a CDN | free |
| Fonts | Google Fonts, with Windows fonts as fallback | free |
| Storage | your browser's localStorage | free |
| Hosting (optional) | Vercel Hobby | free |
| Backend (optional) | Render free web service | free |
| Database (optional) | MongoDB Atlas M0 | free forever |
There is no paid tier and no account to create anywhere.
Honest limitations
Worth knowing before you rely on it:
- It is not an AI / AGI. There is no language model. The tutor is a rules and
dictionary engine: real grammar analysis, but deterministic. It will not
handle an arbitrary complex sentence the way GPT-style models do.
- Sign-in is local by default. With no backend, your account lives in this
browser on this device. Passwords are never stored — only a salted
PBKDF2-SHA256 hash. Clearing browser data deletes it, so use
Settings → Data → Download everything now and then.
- No password reset and no email/SMS verification. Both need a mail/SMS
provider, which is not free at any meaningful volume.
- Translation and OCR need internet. Everything else — lessons, vocabulary,
alphabet, phonics, practice, voice, the sentence explainer — works offline.
- Voices depend on your OS. If Tamil or Hindi sounds wrong or silent,
install the voice: Windows → Settings → Time & language → Language & region →
add the language → Speech.
- Speech recognition needs Chrome or Edge, and an internet connection.
Deploying (free forever)
Frontend → Vercel
npm i -g vercel
vercel --prod
Vercel serves the repository root as a static site; .vercelignore keeps the
server out of the deployment. Nothing to build.
Backend → Render (optional — only for syncing across devices)
The app is complete without this. Add it only if you want the same account on
your phone and laptop.
- Create a free MongoDB Atlas M0 cluster and copy its connection string.
Do not use Render's own free Postgres — it expires after 30 days. Atlas M0
is free with no expiry.
- Push this repo to GitHub, then in Render: New → Blueprint, pick the repo.
render.yaml configures everything.
- Set these in the Render dashboard:
MONGODB_URI — your Atlas stringALLOWED_ORIGIN — your Vercel URL, e.g. https://tamil-bridge.vercel.appJWT_SECRET — generated automatically
- In the app: Settings → Sync, paste the Render URL, press Test
connection.
Render free tier sleeps after ~15 minutes idle, so the first request can take
up to a minute. The app handles this: it stays in local mode and syncs when the
server wakes.
Run the backend locally
cd server && npm install && node index.js
Without MONGODB_URI it uses an in-memory store and warns you — fine for a
smoke test, not for real data.
Project layout
index.html app shell
assets/styles.css dark + light themes, responsive
data/
vocab.js 201 words × 3 languages
alphabet.js Tamil 247 / Hindi varnamala / English 26 (grids generated)
phonics.js 44 English phonemes, Hindi contrasts
lessons.js 10 units, 60 aligned sentences
lexicon.js grammar lexicon + morphology tables
js/
store.js auth.js localStorage + PBKDF2 accounts
speech.js text-to-speech, recognition, scoring
translit.js romanised ⇄ native script
translate.js multi-provider translation
tutor.js sentence analysis engine
check.js spelling + grammar correction
dict.js meaning lookup
srs.js ocr.js sync.js practice, photo OCR, optional cloud sync
i18n.js Tamil / English interface
views.js views2.js screens
app.js router and boot
server/ optional Render backend
Keyboard
| Key | Where | Action |
|---|
Space | Practice | Reveal the answer |
1–4 | Practice | Rate: forgot / hard / good / easy |
Esc | Anywhere | Close a dialog, stop the voice |
