The captioning API for styled, burned-in subtitles
ZapCap renders captions through one API
Send a video, choose a style, get a finished captioned MP4, a transparent overlay, or a green-screen layer back. Not a transcript API — finished captioned video, programmatically. (Prefer a UI? The same engine powers the web editor at zapcap.ai.) Webhook-native. Multilingual. Per-minute pricing.
Captions are the last mile — ZapCap renders them
Transcription APIs return text. Video automation APIs need you to design a template. ZapCap fills the gap in between — finished, styled captioned video, returned by a single task call.
- Not a transcript API — we ship the rendered video, with captions baked in.
- No template to design — no scenes, no timelines, no templates to maintain — one task call.
- Backend-first — a clean REST API for SaaS, agencies, and ad ops — with the zapcap.ai web editor when you want a UI.
Eight product surfaces, one task model
Pick the one closest to your job.
Subtitle API
Video in, styled captioned MP4 out. The main commercial endpoint.
Burned-in subtitles
Captions permanently rendered into the frames. Social-ready.
Video captioning
Async captioning workflow for SaaS, CMS, and product pipelines.
Animated captions
TikTok / Reels / Shorts caption styles, rendered into video.
SRT → burned-in
Approved transcript in, styled MP4 out. No retranscription.
Webhook captioning
Async caption workflows with signed events and retries.
Transparent overlays
Alpha-channel caption layers for NLE timelines.
Green-screen subtitles
Caption layer with chroma backdrop for live + legacy tools.
Three endpoints, the whole API
Upload a video, create a render task, receive a webhook. Everything else — caption layout, transcription, translation, animation — happens server-side.
/videosUpload
Send a remote URL or multipart upload. Returns a videoId.
/videos/:id/taskCreate render task
Pick a templateId, set render options, attach a webhook notification.
/videos/:id/task/:taskIdPoll task (optional)
Webhook-first, but polling works if your stack doesn't accept callbacks.
Pick the format your pipeline wants
Burned-in MP4
Captions baked into the source frames. The right answer for TikTok, Reels, Shorts, ad creative.
Transparent overlay
Alpha-channel caption layer — MOV ProRes 4444 or WebM VP9 alpha — for NLE compositing.
Green-screen layer
Caption layer with #04F404 backdrop, for editors and live tools without alpha support.
Who ships with the ZapCap API
AI video SaaS
Outsource caption rendering instead of building ASR + queue + ffmpeg.
Read morePerformance creative
Turn winning ad concepts into localized caption variants — fast enough to test.
Read moreE-commerce localization
One product video, multiple markets, consistent caption styling.
Read moreTikTok Shop
9:16 safe-zone aware caption variants for cross-border social commerce.
Read moreAgencies
Reusable client-style presets, webhook delivery into your client portal.
Read moreMultilingual rendering
Translate, restyle, and re-render in CJK, Thai, and beyond.
Read moreLanguages most renderers get wrong
Correct segmentation, line-breaking, and glyph shaping for scripts that break naive caption renderers — CJK, Thai, and the wider Southeast Asian set.
Chinese subtitles
Han segmentation and line-breaking that does not split mid-character.
Read moreJapanese subtitles
Kinsoku-aware line breaking and correct kana/kanji shaping.
Read moreThai subtitles
Dictionary word-breaking for a script with no spaces, intact combining marks.
Read moreCJK rendering
One endpoint for Chinese, Japanese, and Korean caption rendering.
Read moreSoutheast Asian captioning
Thai, Vietnamese, and neighbours with correct diacritics and shaping.
Read moreChoose ZapCap when captioning is the job
General video-automation APIs render scenes from templates you design. Transcription APIs return text. ZapCap is the captioning API for existing videos: one task call returns the styled captioned file.
vs Submagic API
Caption-API workflow, pricing, transcript reuse.
Read morevs VEED Subtitles
Workflow control vs marketplace billing.
Read morevs Creatomate
Captioning specialist vs general video automation.
Read morevs Shotstack
Caption task model vs full JSON timeline.
Read morevs Bannerbear
Caption rendering vs image / template automation.
Read morevs JSON2Video
Existing-video captioning vs JSON scene generation.
Read morevs Fal auto-caption
Dedicated caption rendering vs a general model-inference platform.
Read moreCaption pipelines, in production
Anonymized accounts of teams that replaced in-house captioning stacks with the ZapCap API.
AI video SaaS
Seed-stage product shipped captions in one sprint instead of building a rendering stack.
Read moreSocial-video agency
One caption pipeline across every client, delivered by webhook.
Read moreE-commerce localization
One master video, many markets, consistent caption styling.
Read morePerformance creative
In-house ad team turned winning concepts into localized variants on tap.
Read moreThree ways into the captioning API
Past the reference and quickstart above, three guides come at the API from a different angle — a competitor comparison, a worked integration guide, or a production case study.
API alternatives
Honest, date-stamped comparisons against Submagic, VEED, Creatomate, Shotstack, Bannerbear, JSON2Video, and Fal — workflow, pricing, and transcript reuse.
Read moreAPI use cases
Worked end-to-end integration guides for AI video SaaS, performance creative, e-commerce, TikTok Shop, agencies, and multilingual rendering.
Read moreAPI case studies
Anonymized accounts of teams that replaced in-house ASR, render queues, and ffmpeg with a single ZapCap render task.
Read moreDocs, OpenAPI, and AI-assistant citations
API docs
Server-rendered, crawlable, deep-link-friendly.
platform.zapcap.ai/docsOpenAPI spec
JSON + YAML. Codegen your SDK or drop into Postman.
openapi.json/llms.txt
Product summary + priority page index for AI assistants.
llms.txt & llms-full.txtAPI key dashboard
Create keys, set webhook secrets, top up credits.
platform.zapcap.aiPer-minute API credits, usage-based
Pay $0.10/min for rendered video. Volume credits and dedicated capacity are available when you outgrow the dashboard plan.