Knockout API review
A developer-focused background API with alpha video output and self-hosting.
Reviewed by iTechGuides Editors · Editorial team · Updated Oct 2026
Knockout API is a hosted, open-source background-processing API for developers and product teams. It handles video background removal with real alpha-channel output, image cutouts, background replacement, blur compositing, portrait restoration, headshot processing, and layered exports. The API is accessed over REST, with Node, React, Python, CLI, and other SDK options, and it is available through web, API, and self-hosted deployments. Supported video inputs include MP4, MOV, AVI, WebM, and MKV.
The published plans create a clear progression from experimentation to higher-volume use. Free includes 30 images every month, background removal endpoints, no card requirement, and community support. Pay-as-you-go starts at $0.02 per image monthly and adds all endpoints, metered usage, and email support. Knockout Plus costs $10 per month and includes 250 images, layered PSD export, saved presets, custom watermarks, and a lower listed video-processing rate. Volume offers negotiated per-image pricing, an optional negotiated SLA, Slack support, and a usage dashboard. Video processing is reserved for paid tiers.
Its standout capability is transparent video output: asynchronous processing can produce ProRes 4444, WebM with alpha, or opaque MP4 output. Image workflows support PNG or WebP output and batch processing of up to 10 images. The main boundary is scope: clips are limited to 30 seconds, and frames above 1080p are downscaled. Knockout API fits teams that want programmable background processing, flexible deployment, and alpha-video export. Teams needing longer clips or higher video resolution should consider an alternative.
Knockout API pros and cons
- Where it wins
- Real alpha-channel output with ProRes 4444 and WebM export
- Background replacement, blur compositing, and image cutouts
- Open-source API with REST, SDK, CLI, and self-hosting options
- Where it doesn't
- Video processing is limited to 1080p and 30-second clips
- Video background removal is available only on paid tiers
- Free plan is limited to 30 images per month
Knockout API fact sheet, pricing and score →
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