Kling vs Runway: models, clip limits and API prices

Kling and Runway both make AI video models and both sell API access, but they sell different catalogs. Kling's API sells only Kling models, led by Kling 3.0 (3–15 second clips, up to 4K, optional native audio), billed per second in Units drawn from resource packages. Runway's API sells its own Gen-4.5 (2–10 second clips) and Aleph 2.0 next to other labs' models, billed in $0.01 credits, and no Kling model appears in its model list.

Every Kling and Runway fact below comes from that company's own developer docs, read on 2026-09-28 and listed under Sources. Which one makes the better-looking clip is not answered here: run the same prompt on both. The Sume section uses Video generation.

How do Kling and Runway compare?

Can Runway's API run Kling models?

Not today. Runway's models page lists wan3, seedance2_5, grok_imagine_1_5, seedance2, h3_max, aleph2, gen4.5, gen4_turbo, act_two, veo3.1, gemini_omni_flash and a few more, and no Kling id. The reverse holds too: Kling's capability map lists only Kling models. So "Kling vs Runway" is also a choice between one lab's lineup and a catalog that mixes labs.

Kling vs Runway pricing: what does a second cost?

Kling bills per second from resource packages, with the price set by model, resolution and audio. Runway bills credits per second per model, and a generation routed through a Model Router is billed at the rate of the model it picks (Runway pricing). A 5-second clip is 3 Units ($0.42) on Kling 3.0 at 720P without audio, and 60 credits ($0.60) on Gen-4.5.

How do the two APIs differ to call?

Both take a request, return a task id, and finish asynchronously. Kling 3.0 is POST /text-to-video/kling-3.0 with prompt, settings (duration 3–15, resolution, aspect_ratio 16:9, 9:16 or 1:1, audio) and an optional options.callback_url (Kling 3.0 text to video). Runway is POST /v1/text_to_video with a body keyed on model; you poll GET /v1/tasks/{id} until the status is terminal, and output URLs are temporary, so download what you keep (Runway Dev context). Does Runway have an API? covers Runway's keys and SDKs.

Can I call Kling 3.0 without a Kling account?

Yes, through a multi-model API. On Sume today, Kling 3.0 is kling-3 on POST /v1/videos, billed at provider list × 1.25 (Video generation): $0.14 a second silent or $0.21 with audio, plus a 5.5% agent fee by default (API pricing). Runway's Gen and Aleph models are not in Sume's catalog. Kling 3.0 API covers the kling-3 limits, and Sume vs Kling compares Kling's own billing with Sume's.

Which should I pick?

• Pick Kling if you want Kling models only, clips up to 15 seconds, 4K, or its per-second Unit prices.
• Pick Runway if you want its own Gen-4.5 or Aleph 2.0, or several labs' models on one Runway account.
• Pick a multi-model API if Kling 3.0 is one of several models your code calls on one balance.
• Whichever you pick, compare the same resolution and audio setting: every price above changes with both.