Runway API Alternative: Kling, Veo 3 & Seedance, One Key

Runway is not on Aigenway, and we're not going to pretend otherwise. If you're evaluating a Runway API alternative because you want a second vendor, a cheaper per-second rate, or just one gateway for every video model you use, here's the honest comparison — and how Kling, Veo 3 and Seedance cover the same ground behind one API key and prepaid USD billing.

Why Runway isn't here, and what you're trading away

Runway has its own hosted API with its own account, its own credit system, and its own model family (Gen-4, Act-One, and the rest). We don't proxy it, so if a project specifically depends on a Runway-only feature — Act-One's performance-capture face transfer being the obvious one — nothing on this gateway reproduces that exactly, and we'd rather say so upfront than sell you a workaround that quietly falls short. What you gain by switching is the part that isn't tied to a single model: one integration across three strong, independently-trained video models instead of one, and billing you can read from an API instead of a credit-pack dashboard.

What replaces it: Kling, Veo 3, Seedance

These three cover the range most Runway users actually need — cinematic image-to-video, native-audio generation, and fast/cheap iteration:

• Kling — fluid motion and strong image-to-video, plus Motion Control for transferring a reference video's motion onto a character.
• Veo 3 — Google's flagship, with audio (dialogue, SFX, ambience) generated in the same pass as the picture.
• Seedance — ByteDance's model, fast render times and a low cost per second, a good default for volume drafts.

Confirm the live model codes for whichever one you pick before hardcoding a string:

curl "https://api.aigenway.com/v1/methods?provider=kling" \
  -H "Authorization: Bearer sk_live_..."

A concrete call: image-to-video

The most common Runway use case — animate a still you already control — maps directly onto the same request shape here:

curl -X POST https://api.aigenway.com/v1/generations \
  -H "Authorization: Bearer sk_live_..." \
  -H "Idempotency-Key: $(uuidgen)" \
  -H "Content-Type: application/json" \
  -d '{
    "provider": "kling",
    "model": "kling-v2-master",
    "method": "image_to_video",
    "params": {
      "prompt": "slow push-in, rain streaking down the window behind her, cinematic",
      "input_image": "https://example.com/scene.png",
      "duration": 5
    }
  }'

Idempotency-Key makes retries safe — resend the same key on a dropped connection and you get back the same task instead of paying for a second render.

The async task and webhook flow

Video is never synchronous on any provider, Runway included — the POST above returns a task in queued or processing state, not a finished clip. Two ways to get the result:

1. Poll. GET /v1/generations/{task_id} until status becomes succeeded (or failed), then read the output URL off the response.
2. Webhook. Set a callback_url on the request and the gateway POSTs the finished task to your endpoint as soon as it's ready — no polling loop to write.

curl -X POST https://api.aigenway.com/v1/generations \
  -H "Authorization: Bearer sk_live_..." \
  -H "Idempotency-Key: $(uuidgen)" \
  -H "Content-Type: application/json" \
  -d '{
    "provider": "veo",
    "model": "veo-3",
    "method": "text_to_video",
    "params": { "prompt": "a subway train pulls in, brakes hissing, announcement echoing", "duration": 8 },
    "callback_url": "https://your-app.example.com/webhooks/aigenway"
  }'

The task shape — fields, status values, webhook signature — is identical across Kling, Veo 3 and Seedance, so code written against one drives all three. Details in the task lifecycle docs.

Why one gateway beats a Runway-only account

• Three models, one integration. Swap provider/model to compare Kling against Veo 3 or Seedance for a given brief instead of committing to one vendor's look.
• Prepaid per-second USD. One balance, no credit-pack tiers to forecast or top up per provider.
• Production plumbing included. Idempotency keys, a queue, task state and signed webhooks, already built.

If Act-One or another Runway-exclusive feature is the actual requirement, keep your Runway account for that job. For everything else — prompt-driven and image-to-video generation — Kling, Veo 3 and Seedance behind one key cover it, and you can compare all three without rewriting your integration each time.