Should I burn captions in, or use TikTok native auto-captions?

Native auto-captions are fine for one market in one language, but they do not give you the same control over wording, terminology, or placement across storefronts. For cross-border selling, ZapCap renders one approved, on-brand, safe-zone-aware caption track into each market's cut so every upload keeps the same reviewed message.

Can I localize one vertical clip into several markets?

Upload the 9:16 source once with POST /videos, then create one task per market — each with its own translateTo. Each task returns its own localized vertical MP4, so one market failing never blocks the others.

How do I keep product names correct across languages?

Pass product and brand names through the dictionary param as transcription hints so the source transcript gets them right before translation. For copy that must be word-for-word, supply your own approved transcript via the transcript param.

Do you handle CJK and Thai in a tall frame?

Yes — captions are laid out with per-script wrapping, so languages like Chinese and Thai break correctly inside the vertical frame rather than being wrapped on spaces. Set translateTo to the base language code, e.g. zh, not regional variants.

How does billing work for cross-border catalogs?

ZapCap bills per render minute on usage-based credits. Each localized cut is metered separately, so localizing a clip across several storefronts simply consumes credits per render. Check your balance before a large fan-out.

What if I need to build the shop video itself from a product feed?

Use ZapCap to caption and localize finished clips, and pair it with a video automation API for data-driven assembly from your catalog. Our honest comparison pages map out who beats us on which dimension.

Use case · Social commerce

Caption TikTok Shop videos for every market — without colliding with the feed

9:16 safe-zone-aware captions. Translated per market. Backend API

Vertical shop videos lose the message when captions collide with the cart button, the price tag, or the for-you UI. ZapCap is the caption-rendering and translation API that places safe-zone-aware captions and localizes them per market, so cross-border product clips read clearly on every feed.

Caption your shop videos Integration guide

Safe-zone-aware placement · translateTo · webhook delivery

The problem Architecture Backend code State machine Launch checklist Build vs buy Proof FAQ

The problem

Vertical video is unforgiving, and you sell across borders

On TikTok Shop the frame is the constraint. A 9:16 product clip has a cart button, a price tag, and feed chrome fighting your caption for the same pixels — and the buyer reads it in a different language. Place the caption wrong and it sits under the cart; translate it wrong and the hook dies in the new market. ZapCap fixes both in one render call, per market.

UI collision — captions buried under cart, price, and feed chrome.
Safe-zone discipline — top and bottom thirds change meaning per platform.
Cross-border copy — the hook must land in the buyer's language, not a literal gloss.
Vertical re-renders — the same clip re-cut per market by hand.
CJK / Thai layout — wrapping and line-break rules differ by script.
Catalog velocity — new products daily, each needing localized cuts now.

Reference architecture

Where ZapCap sits in your shop pipeline

Run ZapCap behind your seller tooling as the caption layer for finished 9:16 product clips. Your backend sends one vertical source clip, requests a safe-zone-friendly caption preset per market, and files each localized cut back to the storefront that needs it.

Your shop assets

9:16 product clip

Cross-border markets

Source clip in your CDN

Your backend

Localization job runner

Holds ZAPCAP_API_KEY (server-only)

/webhooks/zapcap handler

ZapCap

POST /videos

Task per market · translateTo

Vertical renderUrl

Placement matters most in 9:16: choose a template whose caption position keeps clear of the feed UI, and reuse it across markets so every cut stays in the safe zone.

Backend integration

One vertical clip, a localized cut per market

Upload the 9:16 source once, then fire a render task per market with translateTo and a safe-zone-friendly preset. Each localized cut arrives via webhook, ready to upload per storefront.

WEBHOOK PAYLOAD

{
  "eventId":   "evt_8kQ2...",
  "taskId":    "tsk_2hP4...",
  "event":     "render.completed",
  "renderUrl": "https://cdn.zapcap.../shop-th.mp4"
}

Map taskId → market / storefront when you create the task.
Verify the x-signature header before fetching renderUrl.
Dedupe webhook deliveries on eventId.

1// Localize a vertical shop clip across markets

2const KEY = process.env.ZAPCAP_KEY;

3const ZAP = (path, body) =>

4 fetch(`https://api.zapcap.ai${path}`, {

5 method: 'POST',

6 headers: { 'x-api-key': KEY, 'Content-Type': 'application/json' },

7 body: JSON.stringify(body),

8 }).then(r => r.json());

10const SAFE_PRESET = "<TEMPLATE_UUID>"; // from GET /templates — caption position clear of feed UI

11const MARKETS = ['th', 'id', 'vi', 'zh']; // language codes, e.g. zh (not zh-CN)

13export async function localizeShopClip(clipUrl, productTerms) {

14 const video = await ZAP('/videos/url', { url: clipUrl });

16 for (const lang of MARKETS) {

17 const task = await ZAP(`/videos/${video.id}/task`, {

18 templateId: SAFE_PRESET,

19 translateTo: lang,

20 dictionary: productTerms, // product + brand names as transcription hints

21 // keep words tight so captions stay inside the 9:16 safe zone

22 renderOptions: { subsOptions: { displayWords: 3 } },

23 notification: {

24 type: 'webhook',

25 notificationsFor: ['render'],

26 recipient: 'https://shop.example.com/hooks/zapcap',

27 },

28 });

29 await db.shopCuts.create({ id: task.taskId, market: lang, status: 'processing' });

30 }

31}

State machine

Lifecycle of a localized shop cut

Each market is its own task. Track them so sellers can upload each localized cut to the matching storefront the moment it lands.

pending

transcribing

transcriptionCompleted

rendering

completed

In your seller tool

Show a per-storefront grid — "TH ready, ID rendering, VI queued" — so each cut goes live as it completes.

On webhook

File the renderUrl under the right market and queue it for upload to that storefront.

On failure

Re-run only the failed market; the rest of the localized set is unaffected.

Launch checklist

Before you go cross-border

A short list to keep vertical, localized cuts on-brand and inside the safe zone. Placement, terminology, and delivery in one place.

Talk to integrations Read API docs

Safe-zone caption preset Pick a templateId whose caption position keeps clear of cart, price, and feed UI.
Tight word count per cue Use subsOptions.displayWords so captions never overflow the 9:16 frame.
Product terms in your dictionary Feed product and brand names so transcription gets them right before translation.
Market list as code Drive the cross-border fan-out from one source of truth.
Per-storefront delivery convention File each renderUrl by market so the right cut reaches the right shop.
Webhook signature verified Check x-signature on every payload; dedupe on eventId.
Credit-balance check before a fan-out Cross-border means many renders — confirm balance before queueing.

Build vs buy

The vertical localization stack, honestly

Build it yourself

In-house shop-video pipeline

1ASR + translation wiring — vendors, retries, terminology control.
2Safe-zone layout logic — keep captions clear of 9:16 feed UI.
3Per-cue word fitting — wrapping for CJK / Thai inside a tall frame.
4Render workers — ffmpeg / libass, autoscaling for catalog spikes.
5Per-market tracking — one clip, many localized cuts.
6Output storage — pre-signed URLs, expiry, cleanup.
7Billing meter — per-minute counters across the catalog.

Use ZapCap

Localized vertical captions as a primitive

1POST /videos — upload the 9:16 clip once.
2translateTo per task — a safe-zone cut per market.
3Webhook handler — verify, file by market, upload.

When ZapCap isn't the right answer: if you need to assemble shop videos from product feeds or templated scenes, a broader video automation API (Creatomate, Shotstack, JSON2Video) likely fits better. See our honest alternatives comparisons.

Customer · Anonymized

A cross-border social commerce seller wired the ZapCap API into their seller tooling and localizes every vertical shop clip per market with captions that stay clear of the feed UI

Each new product clip is uploaded once and fanned out into safe-zone-aware, localized cuts per storefront through a webhook handler — instead of an editor manually re-placing captions per market.

Read case study

9:16

Safe-zone-aware placement

per market

One localized cut each

~0 lines

Of ffmpeg / render infra

per-minute

Billing passes through cleanly

For social commerce sellers

Pick a templateId from GET /templates whose caption position sits in the safe zone for vertical feeds, and reuse it across markets. Keeping a tight word count per cue with renderOptions.subsOptions.displayWords also stops captions overflowing the 9:16 frame where the platform UI lives.

Caption shop videos for every market

Backend-only API, webhook-native, from $0.10/min base usage pricing. Safe-zone-aware captions, localized per market, on every feed.

Caption your shop videos Talk to integrations

Caption TikTok Shop videos for every market — without colliding with the feed

9:16 safe-zone-aware captions. Translated per market. Backend API

Vertical video is unforgiving, and you sell across borders

Where ZapCap sits in your shop pipeline

One vertical clip, a localized cut per market

Lifecycle of a localized shop cut

Before you go cross-border

The vertical localization stack, honestly

In-house shop-video pipeline

Localized vertical captions as a primitive

A cross-border social commerce seller wired the ZapCap API into their seller tooling and localizes every vertical shop clip per market with captions that stay clear of the feed UI

For social commerce sellers

Build the rest of the shop pipeline

E-commerce video localization

Performance creative localization

Multilingual subtitle rendering

Burned-in subtitles API

Animated captions API

vs JSON2Video

Case study · E-commerce

Caption shop videos for every market

Caption TikTok Shop videos for every market — without colliding with the feed

9:16 safe-zone-aware captions. Translated per market. Backend API

Vertical video is unforgiving, and you sell across borders

Where ZapCap sits in your shop pipeline

One vertical clip, a localized cut per market

Lifecycle of a localized shop cut

Before you go cross-border

The vertical localization stack, honestly

In-house shop-video pipeline

Localized vertical captions as a primitive

A cross-border social commerce seller wired the ZapCap API into their seller tooling and localizes every vertical shop clip per market with captions that stay clear of the feed UI

For social commerce sellers

How do captions stay clear of the cart button and feed UI?

Should I burn captions in, or use TikTok native auto-captions?

Can I localize one vertical clip into several markets?

How do I keep product names correct across languages?

Do you handle CJK and Thai in a tall frame?

How does billing work for cross-border catalogs?

What if I need to build the shop video itself from a product feed?

Build the rest of the shop pipeline

E-commerce video localization

Performance creative localization

Multilingual subtitle rendering

Burned-in subtitles API

Animated captions API

vs JSON2Video

Case study · E-commerce

Caption shop videos for every market