Kling API: Pricing and Integration Guide

Official Kling AI API prices per second

Official Kling API, API host or web app?

How a Kling API integration works

Kling API pitfalls we hit

1. 01A finished job isn’t always a successful one+

   Symptom

   Failed jobs sit in “processing” forever, and the user’s credits never come back.

   Fix

   Async video APIs can report a job as finished even when the render failed — the failure shows up as a failed status or an error field next to it. Check both before reading the video URL, mark the job failed and refund.

   if (job.status === 'failed' || job.error) fail(job.error)

2. 02Image-to-video field names differ by model version+

   Symptom

   Image-to-video requests fail validation even though the image URL is fine.

   Fix

   Some Kling versions take a start-frame field plus an optional end frame, others a single image field, and end-frame names differ again. Build the request body per model version from the provider’s docs instead of sharing one payload.

3. 03Kling 3.0 text to video can add audio by default+

   Symptom

   Text-to-video clips come back with sound and cost 50% more than you budgeted.

   Fix

   On some APIs the Kling 3.0 text-to-video request generates audio unless you switch it off. Always send the audio setting explicitly, and price audio as its own rate.

4. 04Clip lengths are model-specific+

   Symptom

   Validation errors on requests that look correct.

   Fix

   Kling 3.0 accepts 3 to 15 seconds; 2.6 and 2.5 Turbo accept only 5 or 10; O1 tops out at 10. Some APIs also expect the duration as a string — "5", not 5.

5. 05Result links expire+

   Symptom

   Videos in your users’ libraries start returning 404 a few hours later.

   Fix

   Result links and webhook payloads are only kept for a limited time — sometimes an hour or less. Copy the file to your own storage the moment the job completes, and cut a poster frame yourself if the API doesn’t return one.

6. 06Unsigned webhooks can be forged+

   Symptom

   Anyone who finds your webhook URL can mark jobs as finished.

   Fix

   Verify the signature your API sends with each callback against its published keys, and reject timestamps more than a few minutes off.

7. 07Encode the webhook URL+

   Symptom

   Callbacks with query parameters arrive truncated or not at all.

   Fix

   When the callback URL travels in a query string, pass it through encodeURIComponent (or quote() in Python) first.

   ?webhook=${encodeURIComponent(hookUrl)}

8. 08Keep what the submit call returns+

   Symptom

   Status checks 404 for some models.

   Fix

   Save the job id and any status or result URLs from the submit response and call them directly, instead of rebuilding paths from the model name.

9. 09Never trust a client-sent price+

   Symptom

   Someone edits the request and pays for 5 seconds while rendering 15 in 1080p.

   Fix

   Validate every field against an allow-list per model and compute the charge on the server from your own rate table. The browser only ever shows an estimate.

10. 10Refund exactly once+

    Symptom

    A webhook and a polling job both see the failure and refund the same credits twice.

    Fix

    Make the status change and the refund conditional — UPDATE … WHERE status = ‘active’ RETURNING — so only the first path wins.