Universal workbench

WebVTT to Subtitle JSON

Create Subtitle JSON from WebVTT locally, with no upload or account.

Device-onlyNo uploads. Ever.

Pipelines, branches, presets, naming, and detailed controls

Display

Text sizeDensity High contrast Monospace editor

Quick start

JSON → YAML WebP → PNG SVG → React JSX Plain text → Base64

From

Help me choose the best output Suggested: ASS / SSA

What matters most?

Recommendations use the registered target format and tested fidelity classification. They never inspect or upload your content.

01Input

Drop files or a folder hereChoose WebVTT files or a folder — batch input is welcome

Choose files Choose folder

or paste content

02Configure & run

WebVTTSubtitle JSON

structural conversion · single or batch

Conversion preflightSize, memory, engine, execution, and fidelity before you start

Input: 56 B
Estimated peak memory: 16 MiB
On-demand download: No large engine download
Execution: Responsive local worker
Fidelity: No lossy step declared

What to providePaste WebVTT content or drop a matching file.What you’ll getProduces previewable Subtitle JSON text and a correctly named download.

Useful presetsTransparent, editable settings—not opaque quality labels

Frame rateFrames per second used when reading or writing frame-based MicroDVD subtitles.25Timing offsetShift every cue by this many seconds. Negative values are allowed; cues are clamped at zero.0

Output naming & batch behavior

Filename templateAvailable variables: {output} (converter’s meaningful name), {name}, {target}, {ext}, {index}. Duplicate names receive a safe numeric suffix.

Exampleoutput.json

Pipeline 1 linear · 0 branches

Why use A → B → C?

A pipeline feeds each result directly into the next compatible converter. Use one when the destination needs an intermediate representation or when you want to inspect and normalize that middle format.

JSON → CSV → XLSX turns records into rows before building a workbook.
Markdown → HTML → DOCX resolves markup before creating a document.
SVG → PNG → PDF intentionally flattens vector artwork before placing it on a page.

Only type-compatible next steps are offered. Lossy steps are marked before you run them.

1WebVTT to Subtitle JSONstructural

Add compatible step

Parallel output branchesEach branch receives the final linear result. Branches do not feed or depend on one another.

Add a parallel destination

Processing happens locally. Your file bytes are never sent anywhere.

About this conversion

How to convert WebVTT to Subtitle JSON

Before you start

Paste WebVTT content or drop a matching file.

Accepted: .vtt · text/vtt

Paste valid WebVTT content, choose files, or drag them onto the drop zone.
Confirm the detected format and adjust the available settings. Mixed-format batches are flagged before conversion.
Select “Convert on this device.” Produces previewable Subtitle JSON text and a correctly named download.

How this converter behaves

Subtitle cues are normalized to start time, end time, and text before being serialized into the destination format.

What happens to your data?

The conversion engine runs in this browser tab. OmniCastConverter has no upload API and never sends your content, file name, or converted result to a server.

Fidelity and limitations

This route is classified as structural. The converter preserves meaning and structure supported by both formats.

Basic timing and cue text are preserved; format-specific styling, positioning, and metadata are not.

Try a valid example

The “Use example” action in the workbench loads this exact input. Produces previewable Subtitle JSON text and a correctly named download.

WEBVTT

00:00:00.000 --> 00:00:01.250
Private conversion