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Serverless API (ComfyUI) offers flexible, pay-per-use pricing with no upfront costs. Unlike the Model API (per-request pricing), Serverless API pricing is based on GPU instance uptime for your deployments (billed per second).

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Pricing overview

Serverless API (ComfyUI) supports two billing plans:
  • Pay as You Go: standard hourly rates by machine tier
  • Pro (subscription): 20%–30% discount on Pay as You Go rates
Prices and machine availability may change. Refer to RunComfy Pricing for the latest machine rates, plan benefits, and extras.

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How billing works

Billing is usage-based and calculated per second:
  • Billing starts when an instance is signaled to wake up (cold start + initialization).
  • Billing stops when the instance is fully shut down.
Your deployment can run a mix of persistent and on-demand instances, controlled by:
  • min_instances / max_instances (autoscaling bounds)
  • keep_warm_duration_in_seconds (how long to keep idle instances warm)
See also: Creating a Deployment

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Persistent instances

  • Set min_instances > 0 to keep that many instances running.
  • You are billed for the full uptime (including idle time) until you scale down.

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On-demand instances

  • Additional instances spin up to handle demand above min_instances (or all demand when min_instances = 0).
  • Instances scale down after the keep-warm period.
  • You are billed for cold start, execution, and keep-warm time.

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Instance cost breakdown

  • Cold start: instance boots and loads models/assets. Duration depends on machine tier, workflow complexity, and model size.
  • Execution time: workflows run. This is the main compute time.
  • Keep-warm time: idle time before scale-down. This time is billed.
Note: You may also see Queue Time (waiting for resources or concurrency). Queue time is not billed.

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Support

If you believe you’ve been incorrectly billed, contact us at hi@runcomfy.com with your deployment_id, the request_id (if applicable), and the approximate time of the issue.