> ## Documentation Index
> Fetch the complete documentation index at: https://apixo.ai/docs/llms.txt
> Use this file to discover all available pages before exploring further.
# Kling 2.1
> Kuaishou Kling 2.1 video generation API for standard, pro, and master video workflows
## Overview
Kling 2.1 is a tiered Kuaishou video model for image-to-video generation and master-quality text-to-video generation. Use this page when you are ready to call the API after trying the model in the APIXO playground.
| Capability | Value |
| ---------------- | ---------------------------------------------------------------------------------------------------------------------------------- |
| Model ID | `kling-2-1` |
| Modes | `standard-image-to-video`, `pro-image-to-video`, `master-text-to-video`, `master-image-to-video` |
| Prompt length | 1-5000 characters |
| Duration | `5` or `10` seconds |
| Reference images | None for `master-text-to-video`; exactly 1 for `standard-image-to-video` and `master-image-to-video`; 1-2 for `pro-image-to-video` |
| Aspect ratios | `16:9`, `9:16`, `1:1` for `master-text-to-video` only |
| Output format | MP4 URLs in `resultJson.resultUrls` |
## Endpoint and authentication
Base URL:
```text theme={null}
https://api.apixo.ai/api/v1
```
| Method | Endpoint | Purpose |
| ------ | --------------------------------------- | ------------------------------------- |
| `POST` | `/generateTask/kling-2-1` | Submit a generation task |
| `GET` | `/statusTask/kling-2-1?taskId={taskId}` | Poll task status and retrieve results |
All requests require your APIXO API key:
```http theme={null}
Authorization: Bearer YOUR_API_KEY
```
Submit requests also require:
```http theme={null}
Content-Type: application/json
```
## Copy-paste async quickstart
This minimal request submits a standard image-to-video task and returns a `taskId`.
```bash theme={null}
curl -X POST "https://api.apixo.ai/api/v1/generateTask/kling-2-1" \
-H "Authorization: Bearer YOUR_API_KEY" \
-H "Content-Type: application/json" \
-d '{
"request_type": "async",
"input": {
"mode": "standard-image-to-video",
"prompt": "animate this still life scene with subtle camera movement",
"duration": 5,
"image_urls": [
"https://example.com/source.jpg"
]
}
}'
```
Successful response:
```json theme={null}
{
"code": 200,
"message": "success",
"data": {
"taskId": "task_12345678"
}
}
```
Save the `taskId`; you need it to poll for the final result.
## Poll for result
```bash theme={null}
curl -X GET "https://api.apixo.ai/api/v1/statusTask/kling-2-1?taskId=task_12345678" \
-H "Authorization: Bearer YOUR_API_KEY"
```
Processing response:
```json theme={null}
{
"code": 200,
"message": "success",
"data": {
"taskId": "task_12345678",
"state": "processing",
"createTime": 1767965610929
}
}
```
Success response:
```json theme={null}
{
"code": 200,
"message": "success",
"data": {
"taskId": "task_12345678",
"state": "success",
"resultJson": "{\"resultUrls\":[\"https://file.apixo.ai/xxx.mp4\"]}",
"createTime": 1767965610929,
"completeTime": 1767965710132,
"costTime": 99203
}
}
```
Failed response:
```json theme={null}
{
"code": 200,
"message": "success",
"data": {
"taskId": "task_12345678",
"state": "failed",
"failCode": "SensitiveContent",
"failMsg": "Content violates upstream policy, please adjust the prompt",
"createTime": 1767965610929,
"completeTime": 1767965620132,
"costTime": 9203
}
}
```
Parse `resultJson` after `state` becomes `success`:
```javascript theme={null}
const payload = JSON.parse(data.resultJson);
const videoUrls = payload.resultUrls;
```
## Request body
### Standard image-to-video
```json theme={null}
{
"request_type": "async",
"input": {
"mode": "standard-image-to-video",
"prompt": "animate this still life scene with subtle camera movement",
"duration": 5,
"image_urls": [
"https://example.com/source.jpg"
],
"negative_prompt": "blur, low quality",
"cfg_scale": 0.6
}
}
```
### Pro image-to-video
```json theme={null}
{
"request_type": "async",
"input": {
"mode": "pro-image-to-video",
"prompt": "city skyline timelapse from day to night",
"duration": 10,
"image_urls": [
"https://example.com/start.jpg",
"https://example.com/end.jpg"
],
"cfg_scale": 0.4
}
}
```
### Master text-to-video
```json theme={null}
{
"request_type": "async",
"input": {
"mode": "master-text-to-video",
"prompt": "a futuristic drone flying through neon-lit streets at night",
"duration": 5,
"aspect_ratio": "9:16",
"negative_prompt": "grainy, noisy, static",
"cfg_scale": 0.3
}
}
```
### Master image-to-video
```json theme={null}
{
"request_type": "async",
"input": {
"mode": "master-image-to-video",
"prompt": "turn this product photo into a premium cinematic reveal",
"duration": 5,
"image_urls": [
"https://example.com/product.jpg"
]
}
}
```
## Parameters
Result delivery mode. Use `async` for polling with `statusTask`, or `callback` for webhook delivery.
Required when `request_type` is `callback`. Must be a public HTTPS URL that can receive the final task payload. See [Webhooks](/api-reference/webhooks).
Kling 2.1 input parameters.
Generation mode. Supported values: `standard-image-to-video`, `pro-image-to-video`, `master-text-to-video`, `master-image-to-video`.
Text prompt describing the video. Must be a non-empty string with 1-5000 characters.
Video duration in seconds. Supported values: `5` or `10`.
Reference image URLs. Do not send this field for `master-text-to-video`. Send exactly 1 URL for `standard-image-to-video` and `master-image-to-video`. Send 1-2 URLs for `pro-image-to-video`; the second URL is accepted as an end-frame reference on routes that support tail-frame continuity.
Output aspect ratio for `master-text-to-video`. Supported values: `16:9`, `9:16`, `1:1`. If omitted in `master-text-to-video`, the backend sends `16:9`. Image-to-video modes do not forward this field.
Negative prompt for unwanted visual elements. Maximum length is 500 characters. Blank values are not forwarded.
Prompt guidance scale. Supported range is `0` to `1` with step `0.1`. Recommended range: `0.3`-`0.7`.
## Response format
### Submit task response
`POST /generateTask/kling-2-1` returns a task ID when the task is accepted:
API status code. `200` means the task was accepted.
Human-readable status message.
Unique task identifier used with the status endpoint.
### Status response fields
Unique task identifier.
Current task state: `pending`, `processing`, `success`, or `failed`.
JSON string containing the generated video URLs. Present when `state` is `success`.
Machine-readable failure code. Present when `state` is `failed`.
Human-readable failure message. Present when `state` is `failed`.
Task creation timestamp in Unix milliseconds.
Task completion timestamp in Unix milliseconds. Present after completion.
Processing duration in milliseconds. Present after successful completion and often present after failure.
## Webhook callback mode
Use callback mode when your backend should receive the final result automatically instead of polling.
```bash theme={null}
curl -X POST "https://api.apixo.ai/api/v1/generateTask/kling-2-1" \
-H "Authorization: Bearer YOUR_API_KEY" \
-H "Content-Type: application/json" \
-d '{
"request_type": "callback",
"callback_url": "https://your-server.com/webhooks/apixo",
"input": {
"mode": "master-text-to-video",
"prompt": "a futuristic drone flying through neon-lit streets at night",
"duration": 5,
"aspect_ratio": "16:9"
}
}'
```
The callback payload uses the same unified response format as the status endpoint. See [Webhooks](/api-reference/webhooks) for delivery requirements and retry behavior.
## Billing
Kling 2.1 is billed per generated video. The selected `mode` determines the tier, and `duration` determines the unit price.
| Mode | Tier | 5 seconds | 10 seconds |
| ------------------------- | -------- | --------------- | --------------- |
| `standard-image-to-video` | Standard | `$0.20 / video` | `$0.40 / video` |
| `pro-image-to-video` | Pro | `$0.35 / video` | `$0.70 / video` |
| `master-text-to-video` | Master | `$1.00 / video` | `$2.00 / video` |
| `master-image-to-video` | Master | `$1.00 / video` | `$2.00 / video` |
For current route and market comparison pricing, see [Pricing](https://apixo.ai/pricing).
## Latency and polling
Actual latency may vary by prompt complexity, selected tier, input image size, route, and current queue load.
| Duration | Typical generation time | Recommended first poll | Poll interval |
| ------------ | ----------------------- | ----------------------- | ------------- |
| `5` seconds | 60s-90s | 60s after task creation | 5s-10s |
| `10` seconds | 90s-120s | 60s after task creation | 5s-10s |
For production video workloads, use callback mode to avoid frequent polling. Result URLs are stored through APIXO and are generally available for 15 days, so download important outputs promptly.
Rate limits and concurrency can vary by account, API key, and route. If you receive `429`, slow down requests and retry with backoff. For account-level details, see [System APIs](/api-reference/system).
## Errors and troubleshooting
### HTTP errors
| Code | Meaning | What to do |
| ----- | --------------------------------------------------------------------------------- | ------------------------------------------------ |
| `400` | Invalid request body, missing required field, unsupported mode, or rejected input | Fix the request before retrying |
| `401` | Missing or invalid API key | Check the `Authorization` header |
| `402` | Insufficient balance or quota | Add balance or switch account/key |
| `403` | Key or route cannot access the model | Check permissions and routing settings |
| `429` | Rate limit or concurrency limit reached | Retry with exponential backoff |
| `500` | Server error | Retry with backoff |
| `502` | Upstream service error | Retry with backoff |
| `504` | Upstream timeout | Retry or use callback mode for long-running jobs |
### Task failure codes
Exact `failCode` values can vary because upstream errors are normalized before they are returned.
| Fail code | Meaning | What to do |
| ------------------------------------------------------------------------ | ---------------------------------------------------------------------------------------------------------- | -------------------------------------------------------------------------------------------- |
| `Missing required parameter` | A required field such as `input`, `mode`, `prompt`, `duration`, `image_urls`, or `callback_url` is missing | Add the missing field |
| `Invalid parameter type` | A field has the wrong JSON type | Check `prompt`, `duration`, `image_urls`, `aspect_ratio`, `negative_prompt`, and `cfg_scale` |
| `Invalid parameter value` | A field has an unsupported value | Check `mode`, `duration`, `aspect_ratio`, and `cfg_scale` |
| `Param length exceeded` | Prompt, negative prompt, or image count exceeds the backend limit | Shorten text or reduce image count |
| `ImageNotAccess` | An input image URL could not be fetched | Use a public, direct HTTP(S) image URL |
| `SensitiveContent`, `PromptInvalid`, `ProhibitedContentDetected`, `NSFW` | Prompt, input image, or output failed safety checks | Change the prompt or image |
| `RateLimited` | Upstream rate limit was reached | Retry with backoff |
| `Timeout` | Upstream service timed out | Retry, reduce input complexity, or use callback mode |
| `Unknown error` | Upstream service returned an unmapped error | Retry with backoff or contact support with the `taskId` |
### Common request issues
| Symptom | Likely cause | Fix |
| ---------------------------------- | ----------------------------------------------------------- | ------------------------------------------------------------------------------------------------------- |
| `mode` is rejected | The mode is missing or not one of the four supported values | Use `standard-image-to-video`, `pro-image-to-video`, `master-text-to-video`, or `master-image-to-video` |
| Text-to-video rejects `image_urls` | `master-text-to-video` does not allow reference images | Remove `image_urls` |
| Image-to-video rejects the request | Required image is missing or too many images were sent | Send exactly 1 image for standard/master image modes, or 1-2 images for pro mode |
| `aspect_ratio` appears ignored | The field only applies to `master-text-to-video` | Use `master-text-to-video` when aspect ratio control is required |
| Image URL fails before generation | The backend validates public URL reachability | Use a direct, reachable HTTP(S) URL and avoid private or localhost links |
See [Error Codes](/api-reference/errors) for the full error reference.
## Related links
* [Generation API Overview](/models)
* [Generate Task](/api-reference/generate-task)
* [Status Task](/api-reference/status-task)
* [Webhooks](/api-reference/webhooks)
* [Error Codes](/api-reference/errors)
* [Parameter Specification](/api-reference/parameters)
* [Routing Strategies](/concepts/routing-strategies)
* [Pricing](https://apixo.ai/pricing)