AI Video Generator Tool: Models, Prices and Code (2026)

An AI video generator tool turns a text prompt, a still image or a set of reference shots into a short video clip, and the one you should pick depends less on the brand on the box than on the model underneath it. Canva, CapCut, InVideo and Adobe Firefly all put a friendly editor in front of generative video. If you want control over cost, length, resolution and motion, you can also call the models directly. This guide explains the categories, compares the current video models on price per clip, and shows working code to generate your first video through one API.

What an AI video generator tool actually does

Under the hood, almost every AI video generator tool runs a diffusion model. A diffusion model starts from random noise and removes it step by step until frames appear that match your instructions. Video models do this across time as well as space, so objects keep their shape and motion looks continuous from one frame to the next.

What changes between tools is the kind of input they accept. Four input modes cover nearly everything you will see:

• Text-to-video: you describe the scene in words and the model invents everything. Fast to try, hardest to control.
• Image-to-video: you supply a start frame and the model animates it. Best when the look matters, for example a product shot, a brand illustration or a character you already designed.
• Keyframe-to-video: you supply a first frame, a last frame and sometimes frames in between, and the model fills the motion. This is how you get a planned transition rather than a surprise.
• Reference-to-video: you supply reference images (and sometimes audio or video) of a person, object or style, and the model builds a new scene that keeps them consistent.

Most production work uses image-to-video or reference-to-video, because a still image fixes composition, colour and identity before you spend money on motion. Text-to-video is great for exploring ideas, less great for matching a brief.

Apps, models and APIs: three ways to use an AI video generator tool

When people search for the best AI video generator tool, the results mix three very different products. Knowing which one you need saves a lot of trial subscriptions.

Editor apps

Canva’s AI video generator, CapCut’s AI video generator, InVideo AI and Adobe Firefly sit inside editing products. You get templates, stock assets, captions, music and a timeline. Generation is one feature among many. This suits marketers and creators who want a finished social post in one place and do not care which model rendered the footage.

Avatar and presenter tools

Synthesia’s AI video generator and tools like it focus on a talking presenter reading your script. They are built for training videos, product walkthroughs and internal comms. They are not designed for cinematic B-roll or product animation.

Raw models through an API

The third option is to call the video models directly: Kling, Vidu, Wan, PixVerse, Grok Imagine and others. An API (application programming interface) lets your code send a request and receive the finished video. You choose the exact model, duration, resolution and aspect ratio, you pay per clip, and you can automate hundreds of variations. The trade-off is that there is no timeline editor; you assemble the final cut yourself or in a separate editor.

Some well-known names have also changed. OpenAI has retired the Sora brand, so anyone who built a workflow around the Sora AI video generator needs a replacement model anyway. Going through an API that offers many models protects you from that kind of churn: when one model disappears or a better one ships, you change one string in your request.

Video models you can call through one API

Unicorn API gives you one key and one credit balance for every model in the model catalog. These are the current video models worth knowing, with what each is good for.

Model	Input mode	Lengths and resolutions	Price
Grok Imagine Video 1.5	Image-to-video only	1-15 s; 480p, 720p, 1080p	2.4 / 4.5 / 8 credits per second
Grok Imagine Video 1.0	Text-to-video or image-to-video	6-30 s; 480p, 720p, 1080p	2.4 / 4.5 / 8 credits per second
Wan 2.6 Flash Image To Video	Image-to-video, optional audio, multi-shot option	5, 10 or 15 s; 720p, 1080p	20 credits for 5 s 720p (no audio) up to 180 for 15 s 1080p with audio
PixVerse V6 Max Image To Video	Image-to-video, optional audio	360p, 540p, 720p, 1080p	4.8 to 22.4 credits per second
Vidu Q4 Image To Video	Image-to-video, optional audio	540p up to 4K	7.2 (540p) to 62.4 (4K) credits per second
Vidu Q4 Reference To Video	Reference images and audio	540p up to 4K	7.2 to 62.4 credits per second
Kling 4.0 Keyframe To Video	First, last and in-between frames	720p, 1080p	28.5 / 42.5 credits per second
Kling 4.0 Reference To Video	Reference images, video, voices	720p, 1080p	17 / 25.5 per second with reference video, 28.5 / 42.5 without

How to read that table

• Grok Imagine Video 1.5 has a very low cost per second and strong motion quality, but it only animates a start frame and can be busy at peak times. Its predecessor, 1.0, still matters because it accepts text-only prompts and runs up to 30 seconds at the same per-second rate. There is a deeper look in our guide to creating Grok Imagine videos.
• Wan 2.6 Flash prices per clip rather than per second, and its 5-second 720p tier is the cheapest option here. It also has a multi-shot setting for clips with more than one camera setup.
• PixVerse V6 Max gives you fine control over quality tiers, down to 360p for cheap drafts, and an audio switch.
• Vidu Q4 is the only model in the list that goes to 2K and 4K, and its reference variant accepts reference audio as well as images.
• Kling 4.0 is the most expensive per second, and the one to pick when you need to dictate exactly where a shot starts and ends, or keep a character consistent using reference clips.

What an AI video generator tool costs per clip

Subscription apps hide the per-clip cost inside a monthly fee and a credit allowance. With an API you see it directly, which makes comparison easy. Here is a single worked example: one 5-second, 720p clip, no generated audio.

Model	Calculation	Credits	On a monthly plan ($0.01/credit)
Wan 2.6 Flash	Flat price for 5 s 720p	20	$0.20
Grok Imagine Video 1.5	4.5 × 5 = 22.5, rounded up	23	$0.23
Grok Imagine Video 1.0	Minimum 6 s: 4.5 × 6	27	$0.27
PixVerse V6 Max	8.8 × 5	44	$0.44
Vidu Q4 Image To Video	15.2 × 5	76	$0.76
Kling 4.0 Reference To Video (with reference video)	17 × 5	85	$0.85
Kling 4.0 Keyframe To Video	28.5 × 5 = 142.5, rounded up	143	$1.43

A few things move the number. Audio roughly adds a third to PixVerse at 720p (12 instead of 8.8 credits per second) and doubles Wan 2.6 Flash (40 instead of 20 credits for 5 seconds at 720p). Jumping from 720p to 1080p on Grok Imagine Video 1.5 takes you from 4.5 to 8 credits per second. Going to 4K on Vidu Q4 costs 62.4 credits per second, so a 5-second 4K clip is 312 credits.

Turning credits into a budget

Monthly plans give credits at $0.01 each: Starter is $25, Creator $50, Studio $100 and Pro $200 per month. Top-ups cost $0.015 per credit and never expire. On the Creator plan, 5,000 credits buys about 250 five-second 720p clips on Wan 2.6 Flash, or about 217 on Grok Imagine Video 1.5. Full plan details are on the pricing page.

You never have to estimate, either. The exact price of any request is available before you run it from POST /v1/models/price, which is useful when your app lets users pick length and resolution.

How to generate a video with an API (working code)

If you want to try models before writing code, the video playground runs them in the browser on the same credit balance. When you are ready to automate, every video request follows the same pattern:

1. Create an API key on the keys page and store it as UNICORN_API_KEY.
2. Optionally check the price with POST /v1/models/price.
3. Start a job with POST /v1/jobs, passing a model id and an input object.
4. Poll GET /v1/jobs/{id} until status is "succeeded".
5. Download the video from outputs[0].url.

Python: animate a product photo with Grok Imagine Video 1.5

import os
import time
import requests

API = "https://api.unicornapi.net"
HEADERS = {
    "Authorization": f"Bearer {os.environ['UNICORN_API_KEY']}",
    "Content-Type": "application/json",
}

body = {
    "model": "grok-imagine-video-1-5-preview",
    "input": {
        "prompt": "Slow push-in on the sneaker, soft studio light, "
                  "dust particles drifting, shallow depth of field",
        "image": "https://example.com/sneaker.png",
        "duration": 5,
        "resolution": "720p",
        "aspect_ratio": "9:16",
    },
}

# 1. Check the exact price before spending credits
price = requests.post(f"{API}/v1/models/price", json=body, headers=HEADERS, timeout=30)
price.raise_for_status()
print("Price:", price.json())

# 2. Start the job
resp = requests.post(f"{API}/v1/jobs", json=body, headers=HEADERS, timeout=30)
resp.raise_for_status()
job_id = resp.json()["id"]
print("Job started:", job_id)

# 3. Poll until the video is ready
while True:
    r = requests.get(f"{API}/v1/jobs/{job_id}", headers=HEADERS, timeout=30)
    r.raise_for_status()
    job = r.json()
    if job["status"] == "succeeded":
        print("Video URL:", job["outputs"][0]["url"])
        break
    if job["status"] == "failed":
        raise RuntimeError(f"Job failed: {job}")
    time.sleep(5)

At 720p for 5 seconds, this request costs 23 credits. Because Grok Imagine Video 1.5 is image-to-video only, the image field is what drives the result; the prompt describes the motion.

curl: the cheapest 5-second clip with Wan 2.6 Flash

curl -X POST https://api.unicornapi.net/v1/jobs \
  -H "Authorization: Bearer $UNICORN_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "wan-2-6-flash-image-to-video",
    "input": {
      "audio": false,
      "prompt": "A slow drone shot over a rocky coastline at sunset, waves breaking",
      "image_urls": ["https://example.com/coastline.png"],
      "duration": 5,
      "resolution": "720p"
    }
  }'

Poll the returned job id exactly as in the Python example. To switch models, change the model string and the input fields that model expects. For example, Kling 4.0 Keyframe To Video takes first_frame_url and last_frame_url, and Vidu Q4 Reference To Video takes reference_image_urls. Field lists for every model are in the API documentation.

If you write code in Cursor or Claude Code, you can also let your coding agent call these models directly through MCP; see the agents page.

Picking the right model for the job

The best AI video generator tool is the one that fits the shot. Here is how the models map to common jobs.

Social clips and high-volume testing

Use Wan 2.6 Flash or Grok Imagine Video 1.5. Both put a 5-second 720p clip at around 20 to 23 credits, so you can generate ten variations of an ad hook for the cost of two Kling clips. Draft at 480p on Grok (2.4 credits per second) or 360p on PixVerse (4.8 credits per second), then re-render only the winner at full quality.

Longer single takes

Grok Imagine Video 1.0 runs up to 30 seconds and accepts text-only prompts. A 20-second 720p clip costs 90 credits. Long takes drift more, so keep the action simple.

Clips with built-in sound

PixVerse V6 Max, Vidu Q4 and Wan 2.6 Flash all have an audio option. Turn it on for ambience and effects; for voiceover or music you will usually get better control by generating audio separately and mixing it in.

Planned transitions and storyboards

Kling 4.0 Keyframe To Video takes a first frame, a last frame and optional keyframes in between. When a client has approved a storyboard, this is the model that respects it.

Consistent characters and products

Kling 4.0 Reference To Video and Vidu Q4 Reference To Video build new scenes around reference images. Kling’s reference variant gets cheaper when you supply reference video (17 instead of 28.5 credits per second at 720p). For creating the reference stills in the first place, see our guide to consistent AI characters.

Large screens and premium deliverables

Vidu Q4 is the only option here that outputs 2K and 4K. Use it for the final render, not for exploration.

Free AI video generators: what “free” really means

Searches for an AI video generator tool free of charge are very common, and the honest answer is that video is expensive to compute, so free plans always come with a catch. Typical limits include:

• A small daily or monthly clip allowance.
• Low resolution or short maximum length.
• A watermark on exports.
• Slower queues for free users at busy times.
• Restrictions on commercial use.

Free tiers are good for learning how prompting works. The YouTube videos promising “unlimited long AI videos for free” usually chain short free clips together or rely on trial credits that run out. If you only need a few clips a month, pay-per-use often beats a subscription: a $25 Starter plan is 2,500 credits, more than 100 five-second 720p clips on Wan 2.6 Flash, with no watermark. Top-up credits never expire, so occasional users are not paying for idle months.

For editing, genuinely free options exist. Open-source editors such as Shotcut and Kdenlive cost nothing and are fine for assembling AI clips into a final cut. We cover free-tier limits for a specific model family in our Qwen AI video generator guide.

Common mistakes with an AI video generator tool

1. Writing a story instead of a shot. A 5-second clip holds one action and one camera move. “Camera slowly pushes in as steam rises from the coffee” works. A three-sentence plot does not.
2. Using text-to-video when you have a brand look. If colours, logo placement or a character’s face matter, generate or design a still first and use image-to-video. It costs less in retries.
3. Rendering drafts at full resolution. A 1080p draft on Grok Imagine Video 1.5 costs 8 credits per second; the same draft at 480p costs 2.4. Pick the composition cheaply, then upscale the keeper by re-rendering.
4. Ignoring the minimum and maximum lengths. Grok Imagine Video 1.0 starts at 6 seconds, Grok 1.5 stops at 15, and Wan 2.6 Flash offers 5, 10 or 15. Requests outside a model’s supported values fall back to a default price, so check before you batch.
5. Forgetting audio changes the bill. On Wan 2.6 Flash, audio doubles the price. Leave it off unless you need it.
6. Polling too fast or not at all. Video jobs take time. Poll every few seconds with a timeout, and handle failures instead of looping forever.
7. Locking into one model. Models improve every few months and brands get retired. Keep the model id in a config value so switching from one AI video generator tool to another is a one-line change.
8. Mismatched aspect ratios. Generate 9:16 for Reels and Shorts, 16:9 for YouTube and web. Cropping afterwards throws away resolution and often cuts off the subject.

Pick the model that matches the shot, check the price before you run it, and draft cheap before you render big. That workflow works whether you end up in Canva, CapCut or your own code, and it keeps the cost of every clip visible from the first request.