What is Lucy 2.5?
Lucy 2.5 is the current model in Decart's Lucy line and the one its lucy-latest alias points to; the older Lucy 2.1 stays online for apps pinned to it. It takes a live camera or video stream over WebRTC, applies an edit you describe in text, show with a reference image, or both, and sends back the changed stream, 720p by default.
The same model also edits recorded clips as batch jobs. Tools such as Runway Aleph render a finished clip after you ask; Lucy works on video while it plays. It is sold only through Decart's pay-per-second API, and its weights are not published.
What changed from Lucy 2.1?
Broader, steadier edits at the same price: Lucy 2.5 adds self-anchoring, a fast mode and cleaner removals and effects.
- Edits
- Decart retrained it for more general editing, with effects such as water, fire and sand that react to the scene, whole-scene restyles that keep people and layout, and removals that rebuild the background.
- Stability
- Self-anchoring is new: the model uses its own recent output as a reference, so edits made early in a stream still hold minutes later.
- Speed
- A new inference stack lowers latency, and an optional fast mode, not offered on Lucy 2.1, trades double the price for lower latency still.
- Price
- Unchanged: $0.02 a second live and $0.04 a second for recorded video, the same as Lucy 2.1.
Who is Lucy 2.5 best for?
Lucy 2.5 is best for developers at shopping, advertising, streaming and social apps who want to change people, products and backgrounds in live video while it plays.
Virtual try-on and live shopping
It puts clothing, accessories or products onto a shopper in a live camera feed, so people see an item on themselves before they buy.
Ad variations without reshoots
Products, backgrounds or characters can be swapped in live or recorded footage to make many versions of one ad.
Live streams and social apps
Streamers can change their look, add characters, restyle the scene or add effects such as fire and smoke while they are on air.
Developers building on video
JavaScript, Python, Swift and Android SDKs take a text prompt, a reference image or both, and the reference can change mid-session without reconnecting.
What's included with Lucy 2.5?
Eight kinds of edit from text or a reference image, self-anchoring for long sessions, a faster paid mode, batch editing of recorded clips, and SDKs for web and mobile.
- Eight edit types
- Character swap, virtual try-on, add, replace, remove, background, whole-scene style and visual effects, all from one model.
- Text, image or both
- Describe the change, upload a JPEG, PNG or WebP reference, or combine them, and swap either one mid-session.
- Self-anchoring
- On by default, it reuses the model's own recent frames as a reference so an edit holds steady through long sessions.
- Fast mode
- Lower latency and more throughput at the same quality, billed at twice the standard rate and chosen when you connect.
- Recorded video
- Batch jobs edit MP4 files up to 200MB, in 16:9 or 9:16, with no limit on clip length.
- Client tokens
- Short-lived tokens let browser and mobile apps connect without exposing your main API key.
How does Lucy 2.5 work?
Get an API key
Sign up on Decart's platform, where new accounts get free credits, and create a key.
Connect a stream
Pass a camera or video stream to the SDK, which opens a WebRTC session with Lucy 2.5.
Set and change the edit
Send a prompt, a reference image or both, and replace them at any point while the stream keeps running.
How much does Lucy 2.5 cost?
Lucy 2.5 costs $0.02 per second of live 720p video on Decart's pay-as-you-go API, or $0.04 per second in fast mode or for recorded clips, and new accounts get free credits to test it first.
- 720p video, landscape or portrait
- Streams over WebRTC
- Billed only for seconds of active generation
- Lower latency and higher throughput
- Same output quality as standard mode
- Chosen when the session connects
- Edits recorded clips at 720p
- A 5-second edit costs $0.20
Decart has no subscriptions and no minimum spend; you pay only for what you use. New accounts get free credits to test the API, though Decart does not say how many. A 30-second live session costs $0.60, or $1.20 in fast mode. Lucy VTON 3.5, the dedicated virtual try-on model, has the same prices, and the older Lucy 2.1 costs the same as Lucy 2.5. Volume pricing is arranged by contacting Decart. Full pricing on docs.platform.decart.ai. We checked these prices on .
How do readers rate Lucy 2.5?
No one has rated Lucy 2.5 yet. Be the first.
Sign in to rate. One rating per account.
Lucy 2.5 pros and cons
It edits live video at about 30 fps for $0.02 a second with no subscription, but always-on use adds up, recorded clips stop at 720p, and Decart may train on what you send.
Pros
- Edits a live feed at about 30 fps for $0.02 a second, with no subscription or minimum spend.
- One model covers swaps, try-ons, removals, backgrounds, restyles and effects, steered by text, a reference image or both.
- Self-anchoring keeps a swap or costume locked in over long sessions, even when the person turns away or leaves the frame and returns.
- Early users call the live results impressive, and two independent developers have already wired it into Cinema 4D and 3ds Max viewports.
Cons
- Always-on use adds up: an hour of live editing costs $72, or $144 in fast mode.
- Recorded clips come out at 720p only, below the 1080p that Runway Aleph produces.
- Decart's API terms let it use what you send and what it returns to train its models, though you keep ownership of both.
- It is API only, with no weights to run yourself, and each live session needs about 4 Mbps up and down; Decart advises wired Ethernet for fixed installs.
What are the best Lucy 2.5 alternatives?
Four tools on Recaply do Lucy 2.5's job. VOID is open source, so you can run it on your own server.
Runway AlephPaidChoose it when you edit recorded ads or social clips rather than live video; Aleph 2.0 outputs 1080p, handles multi-shot clips up to 30 seconds and previews the edit first, but costs $0.28 a second on Runway's API.
SwapfaceFreeChoose it when you only need live face swaps for a stream or video call; it runs on your own computer, and live swaps come with its $39-a-month Pro plan instead of a per-second bill.
KreaFreeChoose it when you want to play with live webcam restyling in a browser at no cost; its free plan includes the real-time models with 100 compute units a day, at 512px or 1024px.
VOIDOpen SourceChoose it when object removal in video must run on your own GPUs under Apache 2.0 instead of a per-second API.
Questions about Lucy 2.5
What is Lucy 2.5?
Lucy 2.5 is Decart's real-time video editing model: it swaps people, clothes, objects and backgrounds in a live camera feed while it streams, for developers building shopping, ad and streaming apps.
Who is Lucy 2.5 for?
Lucy 2.5 is best for developers at shopping, advertising, streaming and social apps who want to change people, products and backgrounds in live video while it plays.
Is Lucy 2.5 free?
Not beyond a trial. Lucy 2.5 is pay-as-you-go through Decart's API, but new accounts get free credits to test it before paying. After that, live editing costs $0.02 per second at 720p, and there is no subscription or minimum spend.
How much does an hour of Lucy 2.5 cost?
An hour of live Lucy 2.5 editing costs $72 at the standard rate (3,600 seconds at $0.02), or $144 in fast mode. Decart bills only the seconds the model is generating, and editing recorded video costs $0.04 per generated second.
Is there an open source alternative to Lucy 2.5?
Yes. VOID is an open source tool that does the same job, so you can run your own.
What are the best Lucy 2.5 alternatives?
The closest alternatives on Recaply are Runway Aleph, Swapface, Krea and VOID.
Where can I try Lucy 2.5?
On its official website, decart.ai.
Does Decart train on video I send to Lucy 2.5?
It can. Decart's API terms give it a licence to use your inputs and the outputs to train and improve its models, while you keep ownership of both. Read the API terms and data processing addendum before sending footage of customers or staff.
Can I use Lucy 2.5 to put a real person's face on someone?
Only with that person's verifiable consent and clear disclosure. Decart's acceptable use policy bans deepfakes that impersonate a real person without both, and asks you to label AI-changed video that resembles real people where the law requires it.
What internet connection does Lucy 2.5 need?
Plan for about 4 Mbps up and 4 Mbps down for each live session; Decart measures 1.3 to 2.4 Mbps each way in production. For in-store screens it recommends wired Ethernet and roughly twice that headroom.
Our verdict
Lucy 2.5 is the model to test if your product needs AI edits on live video rather than on finished clips.
It handles swaps, try-ons, removals and effects at about 30 fps from one API, at $0.02 a second with no subscription, and self-anchoring is built to keep edits steady over long sessions.
- Skip it for
- Polished 1080p edits of recorded footage, or teams that cannot let a vendor train on their video.
- Check first
- Run the free credits on your own footage and network, and work out how many live hours a month you will pay for.
Odyssey-2 Pro
Vidi2
Gemini Omni
Seedance 2.5
Kling 4.0
Veo 3.1 Lite