Runway Aleph 2.0 API: aleph2 inputs, limits and price

Yes: Runway Aleph 2.0 has an API. It is the model id aleph2 on Runway's POST /v1/video_to_video: you send a video of 2–30 seconds, an optional prompt of up to 1,000 characters and up to 5 timed keyframe images, and Runway returns the edited video. It costs 28 credits a second, with a 56-credit minimum per generation, and Runway sells credits at $0.01 each.

Every Runway fact below comes from Runway's own developer docs, read on 2026-09-28 and listed under Sources. Sume does not serve Aleph; the last section covers Sume's own prompt-based edit, from its Video Router docs.

What does an aleph2 request take?

Aleph 2.0 edits an existing video: Runway's models page lists its input as "Video + Text/Image". The output keeps the input video's resolution, up to 1080p (complete docs).

How do I call the Aleph 2.0 API?

Create a key in Runway's Developer Portal and send it as a Bearer token with the required X-Runway-Version header. The call returns a task id; poll GET /v1/tasks/{id} until the status is terminal, then download the output, because output URLs are temporary (Runway Dev context). Inputs can be a public HTTPS URL, a data URI or a Runway upload URI. The body below uses only fields from the API reference:

curl -X POST https://api.dev.runwayml.com/v1/video_to_video \
  -H "Authorization: Bearer $RUNWAYML_API_SECRET" \
  -H "X-Runway-Version: 2024-11-06" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "aleph2",
    "videoUri": "https://example.com/clip.mp4",
    "promptText": "Make it night, with wet streets reflecting the shop signs",
    "keyframes": [
      { "uri": "https://example.com/night-look.png", "seconds": 2 }
    ]
  }'

How much does Runway Aleph 2.0 cost?

Runway's pricing lists aleph2 at 28 credits per second with a 56-credit minimum per generation. At $0.01 a credit, a 10-second edit is 280 credits ($2.80), and the 56-credit minimum ($0.56) equals a 2-second edit, the shortest input Runway accepts. Three things add to or affect that:

• prores and png_sequence outputs add 5 credits per second.
• sdr_rec709_10bit adds 20 credits per second.
• A generation stopped by content moderation costs the same as a successful one, per Runway's context page.

What happened to gen4_aleph?

Runway's changelog says Aleph 2.0 arrived on its API on June 2, 2026, and that since July 30, 2026, requests using gen4_aleph fail: replace it with aleph2. The aleph2_alpha id remains a deprecated alias (complete docs). Aleph 2.0 does not deliver native HDR; Runway suggests chaining the edit through its SDR-to-HDR endpoint instead (models). Runway API pricing per second lists the rates for Runway's other models.

Can I edit a video with a prompt on Sume?

Yes, with a different model. In Sume's catalog today, the prompt-based edit is gemini-omni-flash-1.1: you send the source clip in video_url and describe the change in prompt on the Video Router's POST /v1/video-router/generate (Video Router, Video generation). Edit a video with a prompt covers what that request takes, rejects and costs.