Video Image to Video fal.ai

HeyGen Avatar 4

HeyGen Avatar 4 costs $0.600/clip on FairStack — a image to video model for Spokesperson video, Explainers, UGC-style avatars. No subscription required. Pay per generation with full REST API access. FairStack applies a transparent 20% margin on infrastructure cost so you always see the real price.

FairStack price

$0.600/clip

Try HeyGen Avatar 4 API Quickstart Last updated 2026-06-27

What is HeyGen Avatar 4?

Key Features

Text-to-speak or audio-driven

Talking styles + captions

Many aspect ratios

What are HeyGen Avatar 4's strengths?

Premium branded avatars

Flexible input (text or audio)

Caption support

What are HeyGen Avatar 4's limitations?

Face-clear photo required

Avatar-only use case

What is HeyGen Avatar 4 best for?

Spokesperson video Explainers UGC-style avatars

How much does HeyGen Avatar 4 cost?

Metric

FairStack

Details

Price per generation

$0.600

Includes 20% margin

Per-second rate

$0.1000/sec

Billed per second of output

Subscription

None

Pay per generation only

How does HeyGen Avatar 4 perform across capabilities?

HeyGen Avatar 4 — premium avatar

motion quality

85%

visual quality

88%

lipsync accuracy

90%

temporal coherence

86%

character consistency

88%

How do I use the HeyGen Avatar 4 API?

curl

curl -X POST https://api.fairstack.ai/v1/generations/video \
  -H "Authorization: Bearer $FAIRSTACK_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "heygen-avatar-4-i2v",
    "prompt": "Your prompt here"
  }'

Python

import requests

response = requests.post(
    "https://api.fairstack.ai/v1/generations/video",
    headers={
        "Authorization": f"Bearer {FAIRSTACK_API_KEY}",
        "Content-Type": "application/json",
    },
    json={
        "model": "heygen-avatar-4-i2v",
        "prompt": "Your prompt here",
    },
)

result = response.json()
print(result["url"])

Node.js

const response = await fetch(
  "https://api.fairstack.ai/v1/generations/video",
  {
    method: "POST",
    headers: {
      Authorization: `Bearer ${process.env.FAIRSTACK_API_KEY}`,
      "Content-Type": "application/json",
    },
    body: JSON.stringify({
      model: "heygen-avatar-4-i2v",
      prompt: "Your prompt here",
    }),
  }
);

const result = await response.json();
console.log(result.url);

What parameters does HeyGen Avatar 4 support?

Parameter

Type

Default

Details

image_url

string

—

prompt

string (optional)

—

voice

string (optional)

—

audio_url

string (optional)

—

talking_style

enum

stable

Options: stable, expressive

resolution

enum

720p

Options: 360p, 480p, 540p, 720p, 1080p

aspect_ratio

enum

16:9

Options: 16:9, 9:16, 4:5, 5:4, 1:1, auto

caption

boolean (optional)

—

Frequently Asked Questions

How much does HeyGen Avatar 4 cost?

HeyGen Avatar 4 costs $0.600/clip on FairStack as of 2026-06-27. This price includes FairStack's transparent 20% margin on infrastructure cost. No subscription or monthly fee — you pay per generation only. Minimum deposit is $1.

What is HeyGen Avatar 4 and what is it best for?

HeyGen Avatar 4 turns a photo with a clear face into a premium talking-avatar video. Provide text for the avatar to speak (with a voice) or supply your own audio for lip-sync. Supports stable/expressive talking styles, captions, backgrounds, 360p–1080p output, and aspect ratios 16:9/9:16/4:5/5:4/1:1. Billed $0.10/s. HeyGen Avatar 4 is best for Spokesperson video, Explainers, UGC-style avatars. Available via FairStack's REST API with curl, Python, and Node.js SDKs.

Does HeyGen Avatar 4 have an API?

Yes. HeyGen Avatar 4 is available via FairStack's REST API at api.fairstack.ai. Send a POST request to /v1/generations/video with your API key and prompt. Works with curl, Python requests, Node.js fetch, and any HTTP client. No SDK installation required.

How does HeyGen Avatar 4 compare to other video models?

HeyGen Avatar 4 excels at Spokesperson video, Explainers, UGC-style avatars. It is a image to video model priced at $0.600/clip on FairStack. Key strengths: Premium branded avatars, Flexible input (text or audio). Compare all video models at fairstack.ai/models.