Your AI assistant can answer questions and speak. What should users see while they interact with it?
For an AI tutor, voice assistant, or companion app, a custom animated avatar can communicate when the app is listening, preparing a response, or speaking.
But creating that character introduces another set of tasks: illustration, rigging, expressions, mouth movement, animation transitions, and developer controls.
That is the work I help teams with at Mascot Engine.
I’m Praneeth, a Rive animator creating custom interactive mascots and AI avatar animations for web and mobile products.
Building an AI web app that needs an animated character?
Explore Mascot Engine and send me your app screenshot, platform, and avatar requirements.
Your app handles the conversation. The avatar shows its state.
Imagine a language-learning app with an AI tutor.
When the learner speaks, the character looks attentive. While the app prepares a response, the character moves into a subtle thinking animation. When response audio starts playing, its mouth moves with the speech.
These behaviours need a clear connection to the application.
| What happens in your app | What the avatar could do |
|---|---|
| The session becomes available | Settle into a friendly idle |
| The app accepts microphone input | Show an attentive listening expression |
| A response is being prepared | Play a restrained thinking animation |
| Response audio plays | Animate the mouth and speaking expression |
| The learner completes a task | Play a short celebration |
| A connection fails | Show a calm error reaction |
This is an example brief, not a fixed feature package. The right states depend on your product.
The important design decision is to make the avatar reflect what the app is actually doing.
Why use Rive for an interactive AI avatar?
Rive state machines let you connect animations and define the logic for transitions between them. Your character can have different behaviours instead of playing the same animation continuously.
See the official Rive state machine documentation.
Rive also provides runtimes for web, React, Flutter, React Native, and other platforms. Feature support varies by runtime and renderer, so the implementation should be planned around your actual stack.
See the Rive runtime guide.
For a web developer, the goal is an animation asset with clearly documented controls that can be connected to application events.
What can you commission from Mascot Engine?
At Mascot Engine, I provide custom Rive character animation services scoped around your product.
Character design and preparation
Already have a mascot illustration? I can assess how it should be prepared for animation.
Starting with an idea? We can define a character direction around your interface, audience, and brand.
The design should remain readable at its actual display size—not only in a large portfolio preview.
2D rigging and expressions
A character rig makes it possible to animate the face and body consistently.
Depending on the design, the scope can include eyes, eyebrows, mouth shapes, head movement, and gestures.
Activity animations and transitions
We define the behaviours your app needs and how the character moves between them.
For example:
- Idle to listening.
- Listening to thinking.
- Thinking to speaking.
- Speaking back to listening after an interruption.
- Any relevant activity to an error or fallback state.
The transitions deserve attention alongside the individual animations.
Lip-sync controls
A repeating talking loop, audio-driven mouth opening, and viseme-based animation are different deliverables.
We agree on the approach before production, including what data your application will provide.
Developer handoff
The agreed deliverables can include the exported .riv file, animation controls, state mappings, and implementation notes.
The purpose is to give your developer a clear specification for operating the character.
Start with the avatar your first release needs
You do not need to define every future expression before discussing a project.
For an initial voice-based web app, I would consider:
- A calm idle.
- An attentive listening state.
- A subtle thinking state.
- A speaking state with the agreed mouth controls.
- An error or fallback reaction.
Additional expressions, celebrations, outfits, or growth stages can be scoped separately when they support the product.
Need help turning your app idea into an animation brief?
Contact Mascot Engine with your app link or screenshot, existing artwork, and the interactions you need.
What stays in your application?
A custom avatar needs a clear division of responsibilities.
| Animation scope | Application integration |
|---|---|
| Character artwork and rig | AI model and conversation logic |
| Expressions and animated states | Microphone permissions and input |
| Authored mouth shapes and controls | Audio playback and timing signals |
| Animation transition logic | Network status and request handling |
| Documented character controls | Connecting app events to those controls |
The final split should be agreed for your project.
For example, an animator can author a mouth-opening control. Your application still needs to supply values that correspond to the character’s speech audio.
Rive data binding can connect application-controlled data to properties in the character scene. The exact View Model structure and property names should be documented for the authored file.
See the Rive data binding overview.
Make the lip-sync requirement specific
For a simple stylized character, audio-driven mouth opening may be a suitable starting point.
An example specification could define:
-
0as a closed mouth. -
0.5as a medium opening. -
1as the maximum designed opening.
Those values are an example contract, not a universal Rive API.
Your implementation also needs to handle silence, smoothing, playback timing, and interruption.
If you need distinct mouth shapes for speech sounds, discuss a viseme-based system. That requires an agreed shape mapping and suitable timing data from your speech pipeline or analysis layer.
A useful project brief describes the expected result, not just “add lip sync.”
What should be checked before launch?
Test the character inside the real interface.
A few important checks:
- [ ] The mouth closes during silence.
- [ ] Speaking starts with audio playback.
- [ ] Interrupting playback stops mouth movement.
- [ ] The listening state matches actual microphone availability.
- [ ] Rapid state changes do not leave the avatar stuck.
- [ ] Expressions remain readable on smaller screens.
- [ ] Status text remains available alongside visual reactions.
- [ ] Reduced-motion behaviour is defined.
- [ ] Performance is acceptable on target devices.
Agree on who handles each check and how integration feedback will be addressed.
How to request a custom Rive avatar quote
The most useful starting point is a short product brief.
Send:
- Your app: a link, screenshot, or short explanation.
- Your stack: React, another web framework, or a different platform.
- Your character: existing artwork or visual references.
- Required behaviours: listening, thinking, speaking, rewards, or other reactions.
- Voice setup: how speech is generated and played, if already decided.
- Timeline and budget: your target launch date and budget range.
The quote can then account for design complexity, rigging, animation states, lip-sync requirements, transitions, and handoff scope.
Bring your AI avatar idea to Mascot Engine
If you are looking to hire a Rive animator for an AI web app, Mascot Engine is my studio for custom interactive character animation.
I work with founders, developers, and product teams that need a character designed and animated around their application.
Whether you have finished mascot artwork or an early product concept, we can discuss the behaviours your avatar needs and define the animation scope.
Let’s give your AI a face.
🌐 Explore my work: MascotEngine.com
📧 Email your brief: mascotengine@gmail.com
💬 WhatsApp: +94 71 700 0999Send your app screenshot, platform, and required avatar states to discuss a project quote.
Developers: what are you building, and what would you want your AI avatar to do first?
