Avatar API for real-time, interactive video

LemonSlice animates any character from a single photo into a real-time avatar that listens, talks, and responds. Add the Avatar API to the stack you already use, or drop a hosted widget into your site with two lines of code.

  • Ultra-low latency
  • Unlimited custom avatars
  • 1000+ concurrency
  • 24-hr long calls
Microsoft
[LemonSlice] is state of the art. It's so lifelike. It has been such a pleasure for us at Microsoft to work with LemonSlice.
Brad Smith · President of Microsoft
Read case study

From a single image to a live conversation

An avatar API lets your code create and animate a digital character. The LemonSlice Avatar API goes further and animates that character into a live, two-way conversation. Upload one photo, and go from image to a real-time video call with that character. No training, no fine-tuning, no video shoot.

Every avatar runs on a Character World Model, trained from scratch to listen, talk, and act in real time. It is a step past the deepfake and older generative technology behind traditional real-time avatars.

Illustrated character animated by the Avatar API
avatar = lemonslice.AvatarSession(
    agent_image_url="https://example.com/image.png",
    agent_prompt="Talk with hand gestures."
)

What you can build

LemonSlice 2.1 is the default model, and every model runs thousands of concurrent calls. Flash, the Cartoon model, and Pro are there for lower latency, more expressive cartoons, and large-format displays.

Interactive characters for games and entertainment

The Cartoon model is the more expressive option for cartoon companions and NPCs. Real-time image updates change outfits or change scenes without starting a new session.

Tutors for learning and training

Photoreal tutors run on LemonSlice 2.1. The Cartoon model is the more expressive option for cartoon characters. The Action Engine fires gestures and emotion during the call.

Guides for museums, tourism, and airports

Large-format kiosks and exhibits use LemonSlice Pro, the high-resolution model for physical displays, with 24-hour calls.

A face for support, sales, and training

Thousands of concurrent calls, and it is easy to integrate with the voice agent you already use. Flash is the lower-latency model.

Any character. Any style.

LemonSlice is the only interactive avatar model that can animate non-humans, like a turtle or a smiling teacup, as easily as humans.

Update a character's appearance, emotions, and actions during a live session, and swap the source image in under a second.

Built for real-time

Speed and stability are the difference between a demo and production, so the Avatar API is tuned for live conversation.

Ultra-low latency

The fastest response time of any major avatar provider, at 471ms, about the blink of an eye. Read the technical report.

24-hour live calls

Sessions stay live for up to 24 hours without dropping, built for kiosks, installations, and always-on agents.

Live at 24 fps

Every frame is generated in real time from one photo, so replies feel like a real conversation, not a clip.

Thousands of concurrent calls

Run thousands of simultaneous avatar sessions — built for high-volume production workloads.

How interactive avatars work

LemonSlice adds a face layer on top of your voice agent. It works with any TTS and any LLM, so nothing in your stack has to change. Behind the scenes, speech-to-text and voice-activity detection listen, your LLM replies, text-to-speech generates audio, and LemonSlice turns that audio into real-time character video in a WebRTC call.

Cartoon avatar of a woman ready to animate with the LemonSlice API

Step 1: Pick or upload any image.

Upload a photo of any character. No training, fine-tuning, or character rigs required. If it has a face, LemonSlice can animate it.

ElevenLabs v3
Sonnet 4
OpenAI Voice
Gemini Pro
Cartesia Sonic-3
GPT-5.5 Mini
Gemini Audio
Qwen3 235B
Hume

Step 2: Connect any LLM/voice model.

Plug in any language model, voice provider, and knowledge base through LemonSlice's API. OpenAI, Claude, ElevenLabs, Cartesia, and more.

Step 3: Go live with ultra-low latency.

Deploy to your site with a widget, hosted pipeline, or self-managed pipeline. LemonSlice runs at 471ms p99 latency, so conversations feel instant.

Set up an avatar in 5 minutes with our developer-friendly API.

Add LemonSlice avatars to the custom stack you already use or drop a hosted widget into your website with two lines of code. LemonSlice is built to be API-first.

Choose a code example
async def my_agent(ctx: agents.JobContext):

    avatar = lemonslice.AvatarSession(
        agent_image_url="https://lemonslice.com/image.png",
        agent_prompt="Talk with hand gestures.",
    )

    session = AgentSession(
        stt="deepgram/nova-2",
        llm="openai/gpt-5.3-chat-latest",
        tts="cartesia/sonic-3",
    )

    await avatar.start(session, room=ctx.room)
    await session.start(
    )

Let your coding agent add an avatar

Install the LemonSlice skill, then ask Cursor, Claude, or Copilot to add a video avatar to a voice app. The skill checks what you already have. It attaches the avatar to an existing LiveKit agent, or scaffolds the starter app with keys, the voice cascade, an image, and a ringing UI.

$ npx skills add lemonsliceai/skills

Ask your coding agent:

“Add a LemonSlice video avatar to a real-time voice app.”

Models available for every use case

LemonSlice 2.1 is our state-of-the-art model. Available on all plans.

Get started
yourwebsite.com

CWM-1 Lite is our low-cost model for consumer interactive avatar apps

  • Low cost
  • Ultra-low latency
  • High volumes
  • Instant character creation
Request a demo

LemonSlice Pro is our high-res model for large-format displays and physical installations

  • High resolution
  • Physical installations
  • Exceptional visual quality
  • High-fidelity characters
Request a demo

Built for enterprise scale

Multi-region servers

Start the session in the region closest to the client so the media path stays short.

Zero data retention mode

Zero-data-retention mode keeps streaming media and transcripts off disk after a hosted session. Call metadata is still retained.

Pricing

Plans start at $8/mo, and every plan includes API access. The base model runs about $0.16 per included minute. Bring your own LLM or voice model on any tier.

Learn more

Frequently asked questions

An avatar API lets your application create and control a digital character through code. The LemonSlice Avatar API animates a character from a single photo and drives it in a live, two-way conversation, so a user can speak to the avatar and watch it respond in real time.
Any of them. LemonSlice is a face layer on top of the stack you already use, so you keep your own LLM and your own text-to-speech, like ElevenLabs or Cartesia. LemonSlice renders the matching character video in real time.
Any character, in any style, from a single image. LemonSlice is the only interactive avatar model that can animate non-humans as easily as humans, with no recording or model training.
Plans start at $8 a month, and every plan includes API access. The base model runs about $0.16 per included minute, and you can bring your own LLM or voice model on any tier.

The most expressive, interactive avatars. Built to connect.