Moji — on-device emoji suggestions for Kotlin Multiplatform

Why Moji

Built for a keyboard, not a datacenter

No server round trip means no latency budget, no API bill, and no user text ever leaving the phone. Everything runs in-process, in plain Kotlin.

No dependencies

Pure Kotlin inference — no ONNX Runtime, no TFLite, no native code. Nothing else to version-bump, conflict, or bloat your build. Adds about 5 MB to your APK.

Private & offline

The model ships inside the library on every platform. No network calls, no permissions, no telemetry — one less thing to explain in your privacy policy.

Fast

~0.5 ms per suggestion once warm on Apple silicon, ~2 ms on a mid-range phone. Fast enough to run on every keystroke, not just on submit.

22+ languages

Works across languages and scripts. Top-1 and top-5 predictions match a Python reference implementation exactly on all 443 test vectors.

~0.5ms

Per suggestion

once warm, on device

~5MB

On-device

model + tokenizer, inside the library

22+

Languages

1000

Emoji vocabulary

On device

One model, 22+ languages

Real output from the sample app on a Pixel emulator — not mockups. Same model, three languages, no network round trip.

Hindi

"जिम जाना है" → ✅ 👥 📋 👀 🙏

Spanish

"Partido de fútbol esta noche" → ⚽ 🏈 🏀 🏃 🏟️

French

"Réserver un vol pour Paris" → ❤️ 🏆 📝 ✅ ⭐

Same library on every platform

The Kotlin Multiplatform sample app, built from the published artifacts, gives the same result on Android, iOS, desktop and the web.

Android

Pay my bills → 💰 36% · 💸 31%

iOS

Pay my bills → 💰 36% · 💸 31%

Desktop (JVM)

Pay my bills → 💰 36% · 💸 31%

Web (Wasm)

Pay my bills → 💰 36% · 💸 31%

Install

Add it to your build

One line in your Gradle file, from Maven Central. Works in commonMain for Android, iOS, macOS, JVM desktop, JavaScript and WebAssembly. No waitlist, no API key.

Maven Central live

// build.gradle.kts: commonMain, or any platform source set
dependencies {
    implementation("io.github.rajumark:moji:2.0.0")
}

// Gradle picks the right artifact per platform:
// moji-android · moji-jvm · moji-iosarm64 · moji-iossimulatorarm64
// moji-macosarm64 · moji-js · moji-wasm-js

Build with a prompt

Add Moji from rajumark to this Kotlin Multiplatform or Android project.

What it does: on-device emoji suggestions from text, in 22+ languages, ~5 MB, no dependencies, no network.

Install (Maven Central, no extra repository):
  build.gradle.kts (commonMain or any source set): implementation("io.github.rajumark:moji:2.0.0")
  Platforms: Android, iOS, macOS, JVM desktop, JavaScript, WebAssembly

Usage:
  val moji = Moji()
  val top = moji.suggestions("Pay my bills").first()
  top.emoji

Repo: https://github.com/rajumark/moji#readme
Add the dependency, then follow the README for the exact API and current version.

Usage

Three lines to suggestions

Load once, reuse the instance, and call suggestions() on every keystroke — it's thread-safe and fast enough for it.

Kotlin

val moji = Moji()

val top = moji.suggestions("Pay my bills").first()
top.emoji   // "💰"

moji.close()

Java

try (Moji moji = new Moji()) {
    List<MojiSuggestion> s =
        moji.suggestions("Pay my bills");
}

Use cases

Where Moji fits

Anywhere text is composed, one call turns it into an emoji rail — no server, no delay.

Custom keyboards & IMEs

Power a live emoji suggestion bar above the keyboard, updated on every keystroke without leaving the device.

"Pay my bills" → 💰 💸 🧾

Chat & messaging apps

Suggest reactions or inline emoji as a user types a message, the way modern chat apps auto-complete tone.

"Walk the dog" → 🐶 ❤️ 🚶

Social & caption composers

Recommend emoji for post captions and status updates while the user is still writing them.

"Movie night at home" → 🍿 🛋️ 🎬

Support & chatbot UIs

Give automated responses a quick, on-brand emoji reaction without a round trip to a moderation or NLP service.

"Great job thumbs up" → 👍 👏 😎

Notes & journaling apps

Tag entries with a mood or topic emoji automatically, useful for journal timelines and mood tracking.

"Dentist appointment tomorrow" → 👇 🧑‍⚕️ 😬

Reviews & feedback forms

Turn free-text reviews into a quick emoji sentiment tag alongside the star rating, computed on-device.

"Amazing service, highly recommend" → 😍 🔥 ❤️

Notifications & quick replies

Offer emoji-only quick-reply chips generated from the incoming notification text.

"Happy birthday! 🎉" → 😂 🎂 😘

Accessibility & low-effort input

Let users express a full thought with a single tap on a suggested emoji instead of typing it out.

"जिम जाना है" → ✅ 👥 📋

App ideas

20 apps you could build with Moji

Real problems Moji solves today. Pick one and ship it.

Keyboard emoji bar · Suggest the right emoji on every keystroke in a custom keyboard.

Chat composer · Show emoji chips above the send button that match what's being typed.

Caption writer · Add fitting emoji to Instagram-style captions in one tap.

Reaction picker · Suggest the best reaction for a message instead of the same six defaults.

To-do app icons · Auto-icon tasks: "buy milk" → 🥛, "gym" → 🏋️.

Calendar events · Auto-emoji event titles: "dentist" → 🦷, "flight to Goa" → ✈️.

Expense tracker · Auto-tag expenses: "Uber" → 🚕, "pizza" → 🍕.

Shopping list · Turn "apples, bread, eggs" into a scannable 🍎 🍞 🥚 list.

Mood journal · Tag each diary entry with an emoji that matches its mood.

Habit tracker · Give each new habit an icon automatically: "run 5k" → 🏃.

Folder & page icons · Suggest an emoji icon when users name a folder, page or playlist.

Group chat names · Suggest an emoji for new group names like "Goa trip" → 🏖️.

Review & feedback forms · Suggest emoji that match what the user writes in their review.

Notification reactions · React to a message straight from the notification with the right emoji.

Push notification copy · Add a fitting emoji to notification titles automatically.

Friendlier support bots · Add a matching emoji to bot replies so they feel less robotic.

Recipe apps · Show 🧅 🍅 🧄 next to ingredients for quick scanning.

Kids reading app · Show an emoji next to new words to help children read.

Flashcards · Pair each vocabulary word with an emoji to make it stick, in 22+ languages.

Easy expression · Let users who find typing hard pick emoji that match a few words.

Reference

API at a glance

Member	Description
`Moji()`	Loads the bundled model. Implements `AutoCloseable`.
`suggestions(text, limit = 8, skinTone = null)`	Best emoji first. Returns `List<MojiSuggestion>`.
`MojiSuggestion(emoji, name, confidence, supportsSkinTone)`	One ranked result.
`SkinTone.LIGHT … DARK`	Applied to people/hand emoji that support it. `applyTo(emoji)` is also public.

Pricing & license

Free until you're big.

No API key, no sign-up, no license file. Add Moji to your project and ship. It stays free until your product passes 10,000 monthly active devices, and there's never a limit on how often each device runs it.

Start here

Community

Free

For indie developers, startups and growing apps, up to 10,000 monthly active devices.

Commercial use allowed
No API key, account or license file
Unlimited calls on every device
Runs fully on-device, with no tracking or phoning home

Get started

Commercial

Let's talk

For products above 10,000 monthly active devices on any platform.

One license per product, per model
Pricing that fits your scale
Direct support from the people who built it
Early access to model updates

Email WhatsApp Call

Custom models

Built for you

A small, fast on-device model trained for your language, domain or task.

Moderation, classification, detection, replies and more
Tuned on your use case and your users' languages
Shipped as a plain Kotlin library, like Moji
Private: your model runs on your users' devices

Email WhatsApp Call

How devices are counted

A monthly active device is a phone, tablet or other device that runs Moji at least once in a calendar month.

The 10,000 limit applies separately to each product, each platform (Android, iOS, web…) and each Hoverfly model. Crossed it? You have 30 days to get a commercial license.

What the license does not allow

Selling or redistributing Moji or its model on its own, or inside another SDK
Extracting, modifying or fine-tuning the model weights
Using the model or its outputs to train or distill another model
Reverse engineering the model or its file format
Offering it as a hosted API for others

Questions about licensing? Email raju348636@gmail.com or call / WhatsApp +91 63533 21951. Full terms: Hoverfly Community License.

FAQ

Questions

What is Moji?

A Kotlin Multiplatform library (Android, iOS, macOS, JVM desktop, JavaScript, WebAssembly): give it a task or a message and it returns the emoji that fit, ranked by confidence, in 22+ languages.

Does Moji run on device?

Yes. Inference happens entirely on-device in plain Kotlin — no server call, no network permission, no telemetry.

Which platforms does Moji support?

Android (minSdk 21), iOS (device and simulator, arm64), macOS (arm64), JVM desktop, JavaScript and WebAssembly, from Kotlin, and from Java on Android and the JVM. Every platform gives the same results.

How accurate is it?

Top-1 and top-5 predictions match a Python reference implementation exactly on all 443 test vectors across every supported language, with a maximum numerical difference of about 0.0000024 between the two.

How fast and how big is it?

About 0.5 ms per suggestion once warm, and about 5 MB added to your APK for the model and tokenizer.

How much does Moji cost?

Nothing for products with up to 10,000 monthly active devices per platform, including commercial apps. There is no API key or account, and no limit on how often it runs. Above that, a commercial license is needed. See Pricing.

What happens when my app passes 10,000 monthly active devices?

Nothing breaks: Moji keeps working and never checks in with a server. You have 30 days to get a commercial license. Email raju348636@gmail.com or call / WhatsApp +91 63533 21951.

Can you build a model for my app?

Yes. Hoverfly trains custom on-device models for your language, domain or task and ships them as a small library like this one. Get in touch on the same email or number.

Try the real model, right here

Built for a keyboard, not a datacenter

No dependencies

Private & offline

Fast

22+ languages

One model, 22+ languages

Hindi

Spanish

French

Same library on every platform

Android

iOS

Desktop (JVM)

Web (Wasm)

Add it to your build

Three lines to suggestions

Where Moji fits

Custom keyboards & IMEs

Chat & messaging apps

Social & caption composers

Support & chatbot UIs

Notes & journaling apps

Reviews & feedback forms

Notifications & quick replies

Accessibility & low-effort input

20 apps you could build with Moji

API at a glance

Free until you're big.

How devices are counted

What the license does not allow

Questions

What is Moji?

Does Moji run on device?

Which platforms does Moji support?

How accurate is it?

How fast and how big is it?

How much does Moji cost?

What happens when my app passes 10,000 monthly active devices?

Can you build a model for my app?

Moji is one of eight.