Overview

Knockout API combines browser-based image design with image and video processing through an API. It suits developers who need those tools in an application, as well as designers who want a browser Canvas for layered compositions.

Its range is a strength, but the right tier depends on image volume: Free is capped at 30 images a month, while Plus includes 250 and Volume targets 100,000 or more.

Key features

Image tools cover background removal and replacement, blur, foreground isolation, masking, smart crop, batch processing, stickers, outlines, shadows and inpainting. The API also handles upscaling, portrait restoration, colorization and object removal. That breadth makes Knockout more useful than a single-purpose background-removal endpoint for teams building varied image workflows.

Video background removal runs asynchronously, with job polling rather than an immediate finished result. It supports MP4, MOV, AVI, WebM and MKV, clips up to 30 minutes, transparent export and resolutions up to 1080p. The stated warm-call speed for background removal is around 200ms for a 1024×1024 image; a first request after idle can take longer while capacity starts. That distinction matters for applications where latency is visible to users.

The browser Canvas supports layered designs with text and effects, and free accounts can save canvases and cutouts. Developers can use REST or HTTP directly, or official Node, React, Python and CLI options. Knockout manages GPU processing, endpoint updates, usage records, credentials, teams and billing; its GPU infrastructure is powered by Modal.

The privacy policy says uploaded images are processed in GPU worker memory, not stored after the response and not used for model training. It also describes SHA-256-hashed API tokens, Supabase Auth with bcrypt-managed passwords, and TLS-encrypted traffic. EU/EEA users have additional GDPR rights and can contact the company about them.

Pricing

Free costs 0.00 USD per free, recurring, with no expiring signup grant. It allows 30 images a month and 60 requests per minute, with community support. That is enough for evaluation, side projects and open-source work, but the monthly image cap rules it out for sustained production use.

Pay-as-you-go costs 0.02 USD per month, with metered usage billed monthly. It includes all endpoints, email support and video background removal at $0.10/output second; PSD export is an add-on. The paid request limit is 600 per minute, with no monthly image cap. This is the more flexible fit for side projects and early startups, though video costs can add up with longer outputs.

Knockout Plus costs 10.00 USD per month, billed monthly, and includes 250 images a month. It is positioned for designers, agencies and power users. That fixed allowance is a clearer fit when usage is predictable, but its monthly quota is lower than an uncapped paid tier.

Volume has custom pricing and is intended for production workloads of 100,000 or more images per month. Free offers community support, Pay-as-you-go email support, and Volume Slack support. Compare the included quota and support channel with expected usage before choosing.

Platforms

Knockout is available as a web app and API. The browser Canvas serves design work; the API and client options suit software integrations and automated processing.

Who it's for

Choose Knockout if you need several image-processing functions and video background removal from one service, or want to combine API processing with a browser-based design canvas. Free is aimed at evaluation, side projects and open-source work; Pay-as-you-go suits early-stage projects needing uncapped monthly image volume; Plus fits a 250-image monthly workflow; and Volume is aimed at high-volume production.

Look elsewhere if you need a free tier for regular high-volume use, higher-than-1080p video output, or a guaranteed fast first call after idle. The free plan's 30-image cap and the stated cold-start delay are material constraints.

Pros and cons

Pros: A broad image toolkit plus asynchronous video background removal can cover several processing needs through one API.
Pros: Node, React, Python and CLI clients sit alongside REST and generic HTTP access, giving developers multiple integration routes.
Pros: The policy says images are not retained after the response or used for model training, a useful privacy assurance for uploaded assets.
Cons: Free is limited to 30 images a month, so it is for evaluation and small projects rather than ongoing image-heavy use.
Cons: Video output tops out at 1080p, and the first call after idle can take longer than a warm call.
Cons: Pay-as-you-go video is charged at $0.10/output second, making output duration a direct cost factor.

Alternatives

For a free video-removal workflow with a stated 60-second clip limit and transparent WebM export, consider BGRemove.video; it allows three successful removals per 24-hour window. If you want a free Linux CLI, Video Background Remover CLI is another option, though long animated GIFs can become large. For a free web option, RVM-Web is available across web, Windows, macOS and Linux.

Bria Video Background Removal is worth considering if its free 100 generations, cloud-only deployment, 10 requests per minute and queue-based latency suit your needs. For a one-time $6 purchase of 6,000 credits, about four minutes of standard processing and output up to 4K, consider unbg.video.

For broader background-removal browsing, see Green Screen Software, AI Background Removers, AI Video Background Removers and API Mocking Tools. Other listed alternatives include Cutout.Pro, BackgroundRemover.video and Molyin Video Background Remover.

Verdict

Knockout API is a strong fit for developers and creative teams that want broad image processing, video background removal and a browser Canvas in one service. Its main advantage is that range, backed by multiple integration options; its main drawback is the gap between the small Free allowance and the needs of sustained production. Choose it when its 1080p ceiling, quotas and usage-based video cost fit your workflow. Look elsewhere when free volume or higher-resolution video is the priority.

	Knockout API	RMBG
Free plan	Yes	No
Free trial	No	No
Paid from	$0.02/mo	—
Open source	No	No
Platforms	api, Web	api
Free plan	Yes	Yes
Replacement backgrounds	—	Yes
Batch processing	—	Yes
API access	—	Yes

Knockout API vs RMBG

Knockout API

RMBG