YouTube Caption File Checker
YouTube Caption File Checker helps you preflight measurable file, dimension, duration, text, or upload fields before using an official or platform workflow.
The checker returns pass, warn, and fail items, a copy-all result, source references, and local repair links where a TextFaker tool can help.
Choose a file
The browser fills file name, size, and available media dimensions locally. Add missing fields on the right.
Preflight fields
References
- W3C WebVTT Specification
Official W3C specification for the Web Video Text Tracks format.
- YouTube Caption File Formats
Official YouTube Help page describing supported subtitle and closed-caption files.
- MDN WebVTT Format
Developer reference for WebVTT syntax and browser subtitle behavior.
Repair links
YouTube Caption File Checker Guide
What this preflight checks
YouTube Caption File Checker is a base verification utility for measurable fields, not a human review or official approval service. It reads local file metadata where the browser exposes it and accepts manual values for fields that cannot be safely inferred in the browser.
Common checks include caption text size and timestamp structure. Reading speed, line length, overlap, and encoding checks can be expanded as parser presets without creating new page components.
- Caption text format: File extension should be one of: srt, vtt, txt, csv.
- File size limit: File size should be 2.0 MB or smaller.
- Text size: Text input should be 200,000 characters or fewer.
- Timestamp structure: Add caption timestamps such as WEBVTT cues or SRT time ranges.
How to read the result
A pass item means the provided value met the local rule. A warn item means the checker needs more source data, such as page count, DPI, duration, or pasted markup. A fail item names a measurable value that is outside the configured preflight rule.
Use the copy-all button to save the full report with labels, input values, checks, and reference names. That makes it easier to compare fixes before uploading again.
- Pass: the provided measurable value fits the configured rule.
- Warn: the checker needs more local data before it can decide.
- Fail: fix the file, dimensions, duration, text, or naming issue before submission.
Sources and variants
YouTube Caption File Checker stores official or standards references with the base checker. Country, region, or platform variants should be added as data presets only when their source URL, last-verified date, and allowed jurisdiction are present.
This base checker does not publish country variants unless a future preset includes an approved jurisdiction and source-backed rules.
- Source policy: official-required.
- Base variant count planned: 0.
- Demand proof URLs stored: 2.