Animated Captions API

The word-by-word caption look, rendered at scale

The bouncing, popping, karaoke-style captions that hold attention on TikTok, Reels, and Shorts — often searched as dynamic captions or dynamic subtitles, generated programmatically. Send a clip and a style, and ZapCap renders the animation into the frames. No frame-by-frame keyframing, no After Effects, no template-builder UI.

Create API key Read API docs

Word-pop · karaoke fill · keyword emphasis · animation baked into the MP4

Workflow Demo Styling Transcripts Output modes Languages Pricing Proof FAQ

Animation, not just text

How creators get this look — and why an API beats it at scale

The animated caption style is hand-built in editing apps one clip at a time. To produce it across hundreds of videos, you need it as a render parameter, not a manual edit.

OPTION 01

Manual caption editor

CapCut · Submagic · creator apps

Great for a single clip
Hand-edit every video
No programmatic access
Doesn't scale to a pipeline

OPTION 02

After Effects / keyframing

Motion graphics by hand

Total creative control
Slow, expensive per clip
No API to drive it
Hard to standardize a look

OPTION 03 · YOU ARE HERE

ZapCap · animated caption rendering

Animation as a render parameter

Word-pop, karaoke, scale bumps
Toggle animation per task
Rendered into the frames
Same look across every clip

OPTION 04

Static subtitle file

SRT / VTT generators

Timed text only
No animation
No styling
Off by default on social

API workflow

Animated captions in a few calls

Upload a clip, create a task with animation enabled and a templateId, then poll or get a webhook. ZapCap renders the word-by-word animation into the frames and hands you a finished MP4.

1
Upload your video
POST the file to /videos. We stream it to storage and hand you back a videoId.
POSTPOST /videos
2
Create the captioning task
One POST starts transcription, styling and rendering with your chosen template. Add a notification webhook to skip polling.
POSTPOST /videos/:id/task
3
Receive the webhook
We POST status updates to your endpoint as the render moves through transcribing → rendering → completed.
HOOKPOST → your URL
4
Download the finished render
Burned-in subtitles, served from a global CDN. No watermark. MP4 ready for any social platform.
GETGET renderUrl

Step 1 / 4·~2s

1import { readFileSync } from "node:fs";

3const form = new FormData();

4form.append(

5 "file",

6 new Blob([readFileSync("clip.mp4")]),

7 "clip.mp4",

8);

10const { id: videoId } = await fetch(

11 "https://api.zapcap.ai/videos",

12 {

13 method: "POST",

14 headers: { "x-api-key": process.env.ZAPCAP_KEY! },

15 body: form,

16 },

17).then(r => r.json());

POST /videos·Upload your video

Live render

Same hook, four animated styles

Each clip is the same source with animation on and a different templateId. The motion is rendered into the pixels — it plays the same in every feed, with no client-side animation engine.

Beast preset

Hormozi preset

Tracy preset

Devin preset

Source is a 9:16 vertical clip. Animated captions are baked into the frames, so the pop, fill, and emphasis survive download and re-upload to any platform.

Styling as an API primitive

Pick the motion

Tune the emphasis.

Send a templateId for a complete animated look, or control the motion directly. Animation, word-by-word reveal count, keyword emphasis, font, and position all toggle independently on the task body.

Animated templates — Beast, Hormozi, Tracy, Devin, plus 25 more (29 presets) — each captures a complete animated caption look.
Animation — word-by-word pops, karaoke fill, fade in/out, scale bumps — switched on per task.
displayWords — control how many words appear per cue so the reveal pacing fits the edit.
Keyword emphasis — flag punchwords; ZapCap colors / scales / boxes them so the hook lands.
Layout — font, color, stroke, shadow, vertical position with safe-zone math.

Try a style

Render options

{
  "templateId": "46d20d67-255c-4c6a-b971-31fddcfea7f0",
  "renderOptions": {
    "subsOptions": {
      "emphasizeKeywords": true,
      "animation": true,
      "displayWords": 2
    },
    "styleOptions": {
      "fontUppercase": true,
      "fontShadow": "l"
    }
  }
}

Two transcript paths

Auto-transcribe — or bring your own

Auto-transcribe

ZapCap transcribes and times the words so the animation lands on the right beat. Edit any cue, then render the animated captions against the approved transcript.

Inspect the transcript on the task status, edit via PUT /videos/:id/task/:taskId/transcript
Word-level timing drives the per-word animation
Re-render the same transcript into multiple animated styles

Bring your own transcript

Have approved cues already? Send them and ZapCap animates them without retranscribing — handy for scripted hooks and repurposed long-form clips.

Supported via the SRT-to-burned-in workflow
Preserve approved wording and punchlines
Animate the same script into N variants for A/B testing

Output modes

Animation baked in — overlay it if you prefer

Most common

Burned-in MP4

The animated captions are rendered into the source frames — the pop and fill play identically on TikTok, Reels, and Shorts, with sound off.

.mp4 · h264

Editor-friendly

Transparent overlay

The animated caption layer with alpha preserved, so you can drop the motion over your own cut in an NLE — no chroma key.

.mov ProRes 4444 · .webm VP9 alpha

Compatibility

Green-screen layer

For tools without alpha support. Animated captions on a #04F404 canvas you key out in your editor or live tool.

.mp4 · #04F404 backdrop

Burned-in animated captions are the standard for short-form social. Choose an alpha overlay only if you composite the animated captions over your own edit downstream.

Multilingual animation

Animate captions in any language

Set a target language and ZapCap transcribes, translates, and animates captions in that language. CJK and Thai use language-aware line-breaking so per-word animation lands on real word boundaries, not whitespace.

Repurpose one clip into animated captions for multiple markets
A brand-term dictionary keeps product names accurate in the animated text
Language-aware word splitting for Chinese, Japanese, Thai

Wait for it

等一下

รอดูตอนจบ

Simple API credits

Per-minute, usage-based credits

Pay for the minutes you render. Animation is part of the render — no separate motion-graphics fee. See pricing for the full multiplier table.

Top up credits to keep clips flowing in production
Volume credits available at scale
No per-seat fee — pay for renders, not users

$0.10 / min

Indicative starting rate. Final pricing depends on render mode and output format. API access requires a Pro plan plus credits.

View full pricing Talk to us about volume

Customer · Anonymized

A short-form content studio produced animated captions across hundreds of clips a week by making the look a render parameter instead of a manual edit

Editors stopped hand-animating captions per video. One templateId and an animation flag now produce a consistent, on-brand animated look on every clip, rendered into the frames and ready to post.

Read case study

hundreds

Clips a week, one consistent look

1 flag

Animation toggled per task

in-frame

Motion survives every re-upload

on-brand

Same style across all editors

About the Animated Captions API

Animated captions reveal and emphasize words with motion — word-by-word pops, karaoke-style fills, fades, and scale bumps — instead of showing a static block of text. Teams also call them dynamic captions or dynamic subtitles. ZapCap renders this animation into the video frames programmatically for TikTok, Reels, and Shorts.

Keep exploring

Render animated captions through the API

Create a key on a Pro plan and buy credits in the dashboard.

Create API key Read API docs

Animated Captions API

The word-by-word caption look, rendered at scale

How creators get this look — and why an API beats it at scale

Animated captions in a few calls

Upload your video

Create the captioning task

Receive the webhook

Download the finished render

Same hook, four animated styles

Pick the motion

Tune the emphasis.