Knockout API

Knockout API is a browser workspace and developer API for image editing, enhancement and asynchronous video background removal. It fits developers building varied media workflows, plus designers who want layered compositions without leaving a web app. The main decision is whether its quotas and metered video pricing match your production volume.

Overview

Knockout combines a Canvas editor with API access to a broad set of image operations. The Canvas supports layered designs, text and effects, and free accounts can save canvases and cutouts. For software teams, REST and ordinary HTTP requests are supplemented by official Node, React, Python and CLI clients, reducing the integration work for common stacks.

The service also handles GPU processing, endpoint updates, usage records, credentials, teams and billing, with infrastructure powered by Modal. Uploaded images are processed in GPU-worker memory, deleted after the response and not used to train models. API tokens are SHA-256 hashed, passwords use Supabase Auth with bcrypt, and traffic is encrypted with TLS. EU and EEA users have GDPR rights. These protections make it a more credible choice for applications handling user imagery, although your own data-handling obligations still apply.

Key features

Image functionality goes well beyond cutouts: background removal and replacement, blur, foreground isolation, masking, smart crop, batch processing, stickers, outlines, shadows and inpainting are all covered. Enhancement endpoints add upscaling, portrait restoration, colorization and object removal. That range suits a product that needs several image transformations rather than a single-purpose remover.

Video background removal is asynchronous. Your application submits a job and polls for completion, so it is appropriate for queued or workflow-based processing rather than an instant preview. MP4, MOV, AVI, WebM and MKV inputs are supported, with clips up to 30 minutes, transparent-video export and output up to 1080p. Warm background-removal calls are stated at about 200ms for a 1024×1024 image; the first request after idle can take longer while capacity starts, an important caveat for user-facing latency.

Free usage allows 60 requests per minute and 30 images per month. Paid tiers raise the rate limit to 600 requests per minute and remove the monthly image cap. Those limits are generous for prototyping but the free image allowance is quickly exhausted by regular content operations.

Pricing

Free

The Free plan costs nothing, billed recurring, with 30 images each month and no expiring signup grant. Community support is included. It is aimed at evaluation, side projects and open-source work; the 30-image ceiling makes it unsuitable for a live service with steady traffic.

Pay-as-you-go

Pay-as-you-go starts at $0.02 a month, with metered usage billed monthly and all endpoints included. PSD export is an add-on, and video background removal costs $0.10 per output second. Email support replaces community support. This is the practical step up for side projects and early startups that need uncapped monthly image usage while retaining usage-based spending, but video-heavy workloads can become expensive as clip duration grows.

Knockout Plus

Knockout Plus costs $10 a month, billed monthly, and includes 250 images each month. It is positioned for designers, agencies and power users. The fixed allowance is easier to budget than metered image use, but it is only a modest increase over Free for teams processing more than a few hundred images and does not remove the separate video charge stated for Pay-as-you-go.

Volume

Volume has custom pricing and is designed for production workloads processing 100,000 or more images per month. Slack support is included. It is the tier to discuss for high-throughput operations; smaller projects gain little from entering a volume negotiation.

Platforms

Knockout runs through a web app and an API. Integrations are available via REST, any HTTP client, and official Node, React, Python and CLI clients. Video inputs include MP4, MOV, AVI, WebM and MKV; maximum export and processing resolution is 1080p, and maximum clip length is 30 minutes.

Who it's for

Choose Knockout when one product needs cutouts, replacement backgrounds, enhancement, batch work and video matting behind a consistent API. It is especially suitable for developers who value client libraries and for designers who want a browser Canvas alongside automation. Free is sensible for experiments and open-source projects; Pay-as-you-go fits early products; Plus suits recurring design work; Volume is reserved for very large production pipelines.

Look elsewhere if you need a large free allowance, synchronous video results, output beyond 1080p, or predictable video costs independent of output duration.

Pros and cons

Pros

• Broad image coverage: enhancement, inpainting, masking and batch tools reduce the need to combine several APIs.
• Developer-friendly access: REST plus Node, React, Python and CLI options fit common application stacks.
• Useful video scope: five input formats, 30-minute clips, transparent export and 1080p output cover substantial jobs.
• Clear privacy and security measures: images are not retained after responses or used for training, with hashed tokens and encrypted traffic.

Cons

• Small free quota: 30 images per month is mainly for evaluation.
• Asynchronous video workflow: polling adds implementation and user-experience complexity.
• Metered video pricing: $0.10 per output second makes long or high-volume clips harder to forecast.
• Cold-start latency: the first request after idle can exceed the stated warm-call speed.

Alternatives

Cutout.Pro is a better fit when you want Android and iOS apps as well as API and desktop coverage, with subscriptions starting at 5.00 USD monthly for 80 credits.

unscreen.io suits browser-first video work when its free tier's unlimited browser processing, up to 1080p and no time limit matter more than sound, bitrate or format flexibility.

Background Eraser is the alternative for users who prefer iOS, macOS, web or Windows editing with a free plan that includes all recording and editing features, accepting watermarks on exports.

BackgroundRemover is preferable when a free, open-source, locally installable tool is the priority.

Robust Video Matting is a free, GPL-3.0 project offering pretrained models and source code for self-managed deployments.

VCam is aimed at desktop workspace use, with a free Starter plan limited to three members, 500MB storage and watermarks.

PixelZap is a mobile-focused alternative for Android, iOS and macOS.

UniFab Video Background Remover AI is the straightforward choice for a completely free, watermark-free desktop video remover with customizable background colors.

Verdict

Knockout API is a strong choice for developers and creative teams that need many image operations, a usable browser Canvas and video background removal in one service. Choose it for breadth, client options and production support tiers; look elsewhere if your priority is a generous free quota, instant video responses or tightly predictable long-video costs.