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Runway Video Generation
runway / extend-ai-video
Commercial usePart of the Runway API family — compare all Runway models →

Step into the future of content creation with the Runway API, powered by Runway AI's groundbreaking Gen-4 architecture. Available through Kie.ai, this toolkit transforms ideas into stunning videos using the Runway Gen 4 Turbo API. Whether you're generating from text or converting images to dynamic footage, Runway AI image to video capabilities deliver professional results instantly.

Model Type:
Pricing: 720p costs 12 credits per video (≈ $0.06), 1080p cost 30 credits per video (≈ $0.15) High-tier top-ups include a +10% bonus, making effective pricing approximately 10% lower than listed.
Input

The taskId must be a valid taskId returned from the video generation interface. Note: Video generated after 1080P cannot be extended.

Describe the text prompt for extending the video content.

Video resolution.

Output
video placeholder

Enter a task ID to get the video version of your video.

README

Complete guide to using Runway Video Generation

Runway API: Revolutionize Video Creation with Gen-4 Turbo on Kie.ai

Discover the Runway API on Kie.ai, featuring Runway Gen 4 Turbo for seamless AI text-to-video and image-to-video generation. Boost your projects — no subscriptions needed.

What is Runway API?

The Runway API is a powerful interface to Runway AI's advanced video generation models, accessible via Kie.ai for developers and creators alike.

Next-Gen Video Synthesis:

Runway API leverages Runway Gen 4 Turbo to create high-fidelity videos from text prompts or images, ensuring temporal coherence and cinematic quality.

Seamless Integration Tool:

Designed for easy embedding into apps and workflows, the Runway API generates videos from a text prompt or an image in a single request, without complex software.

Accessible AI Innovation:

Through Kie.ai, users get instant Runway API keys with credit-based pricing, making Runway AI's tools available without barriers for experimenting with Runway AI image to video features.

Key Features of Runway API

Gen-4 Turbo Acceleration:

The Runway Gen 4 Turbo API generates 5- or 10-second videos at 720p, or 5-second videos at 1080p, from a text prompt or a reference image, which suits rapid prototyping.

Extend AI Video:

The Runway API allows users to extend existing AI-generated videos to create longer sequences while maintaining visual consistency and motion coherence.

Credit-Efficient Usage:

Kie.ai's credit system for Runway API lets you pay only for what you use, with no subscriptions, optimizing costs for Runway Gen 4 Turbo API projects.

Why Choose Us?

High-Quality Videos with Runway API

Kie.ai uses the power of Runway API to generate high-quality, professional videos. Whether converting images or text to video, you can expect exceptional clarity and detail in every project.

Fast Runway Video Generation with Kie.ai

With Kie.ai, enjoy rapid video generation powered by the Runway API. We ensure quick turnaround times so you can meet even the tightest deadlines without sacrificing quality.

Affordable Runway API Pricing

Access powerful video creation tools through Kie.ai at competitive prices. Our flexible pricing plans for the Runway API make advanced video generation affordable for businesses and creators alike.

How to Use Runway API on Kie.ai

Getting started with Runway API is straightforward with Kie.ai's user-friendly process.

  • 1. Sign Up for Your Kie.ai Account:

    Create an account on Kie.ai to access the Runway API and its features, including the Runway Gen 4 Turbo API.

  • 2. Create Your Runway API Key:

    Log in, go to the Key Management section, and generate your Runway API key instantly—no approvals needed.

  • 3. Integrate and Experiment:

    Use the key in your projects, referring to Kie.ai's Runway API documentation for integration guides and a playground to test prompts.

  • 4. Generate and Refine:

    Send a text prompt, with an optional reference image, via the Runway API (or extend a clip you generated earlier), adjust prompts for optimal results, and download your creations.
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User Feedback

See what our users have to say about our product

The video quality generated by the Runway API through Kie.ai is exceptional. With the Runway Gen 4 API, my projects have never looked better. It’s a game-changer for content creators!

John Smith

Product Manager

Thanks to the Runway AI API, we can quickly produce stunning videos for our marketing campaigns. The Runway API key integration was seamless, and the process is incredibly fast.

Sarah Johnson

Designer

The pricing for the Runway API on Kie.ai is highly affordable. With access to the Runway API, I get professional results at a fraction of the cost, making it perfect for my studio’s needs.

Mike Davis

Technical Director

Frequently Asked Questions

Here are some common questions and answers

Q

How do I get a Runway API Key?

A

Create an account on Kie.ai and generate a key on the API Keys page (kie.ai/api-key) — no subscription or approval needed. Send it as the header Authorization: Bearer YOUR_API_KEY and call POST https://api.kie.ai/api/v1/jobs/createTask with model set to runway and an input holding prompt, duration and quality (plus image_url for image-to-video). The request returns a taskId: pass a callBackUrl to be notified when the video is ready, or poll GET /api/v1/jobs/recordInfo?taskId=…. This key works with the Runway endpoint on Kie.ai; Runway's own developer API uses separate keys.

Q

How does Runway API pricing work?

A

Runway on Kie.ai is billed per video: a 5-second 720p video costs 12 credits (~$0.06), and a 10-second 720p or 5-second 1080p video costs 30 credits (~$0.15). Extending a clip costs 12 credits at 720p or 30 credits at 1080p. Credits are pay as you go, with no subscription, and never expire (1 credit ≈ $0.005; larger top-ups add bonus credits, for example 10% on a $1,250 top-up). Prices may be updated; the pricing card at the top of this page always shows the current rate.

Q

Where can I find Runway API documentation?

A

You can access the full Runway API documentation at Kie.ai, including input formats, response handling, and best practices. A built-in playground is also available to test prompts without writing code.

Q

Does Runway have its own API?

A

Yes. Runway offers its own developer API, documented at docs.dev.runwayml.com, with its own keys and Runway credits. The Runway API on Kie.ai is a separate way in: you use a Kie.ai API key and Kie.ai credits, and the same key and credit balance also cover the other video, image, music and chat models on Kie.ai. Kie.ai's Runway endpoints and parameters are documented in the Kie.ai Runway API docs.

Q

How can I improve the quality of generated videos?

A

Describe the subject, action, style and setting specifically (prompts can be up to 1,800 characters). When you pass an image_url, describe how the image should move; the output then follows the image's aspect ratio, while text-only requests need an explicit aspect_ratio. Choose 1080p for 5-second clips (10-second clips are 720p only), and use Extend AI Video to continue a clip you like in the same aspect ratio.