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CaptionPass

Professional caption delivery QA for editors and producers.

Product

  • Free caption converter
  • Fix captions
  • Pricing
  • What is CaptionPass?
  • API
  • Sign in
  • Dashboard
  • Enterprise

Learn

  • SRT vs VTT
  • YouTube caption upload issues
  • Why your captions are not showing
  • Fix overlapping subtitles
  • Educators
  • All guides →

Legal

  • info@captionpass.com
  • Privacy
  • Terms

© 2026 CaptionPass. Caption reliability layer for delivery.

CaptionPass

Free caption converter · Professional delivery QA

Free caption converter — with delivery QA and a full audit trail

Convert SRT and WebVTT for YouTube, TikTok, HTML5, and LMS delivery. Download upload-ready output, optionally grab CaptionPass enhanced formatting — every fix is named and traceable, not a silent black-box conversion.

Convert & fix freeFree caption converterTroubleshooting guides
Delivery reportinterview-ep12.srt
Platform-compliantAccessibility82/100
  • ✓Timecode format00:01:23,456 → 00:01:23.456
  • ✓WEBVTT header addedRequired for HTML5 / YouTube
  • ★Reading speed21 → 16 cps on 3 cues

✓ Required = platform will accept · ★ Recommended = accessibility boost

Free caption converter
Upload a subtitle file, pick a delivery preset, and download upload-ready export — plus optional CaptionPass enhanced formatting. One run, two downloads, full QA report.

Named fixes — before & after

Before

00:01:23,456 --> 00:01:26,120

This cue has fast reading speed and comma timecodes.

Explainable fixes
Every transformation is named and tied to a cue index. Audit before you re-upload to a client or platform.
Platform-aware presets
Line length, reading speed, and styling rules for YouTube, TikTok, HTML5, LMS/TTML, and a generic safe baseline.
No account for free tier
Ephemeral processing on the public tool — up to 5 successful runs per UTC day. Your file is not stored.

How it works

  1. 1

    Upload

    Drop SRT, VTT, SBV, ASS, TTML, or CaptionPass JSON IR.

  2. 2

    Fix & report

    Pick a delivery preset. See diagnostics, warnings, and applied fixes.

  3. 3

    Download

    Export a clean file ready for upload — with confidence in what changed.

Inside CaptionPass

The free tool gets one file out the door.
The dashboard runs your whole pipeline.

Save any file to a project and CaptionPass tracks it end to end — a live work queue, two-axis delivery QA, and an audit trail your clients and platforms can trust.

  • Work queue that surfaces exactly what needs action before delivery
  • Two-axis QA on every file — platform-compliant vs. accessibility-enhanced
  • A full audit trail: every fix named and traceable back to its cue
Open your dashboardSee plans
app.captionpass.com/dashboard

This month

Proof of value across your projects

Files this month

34

delivered

Media minutes

612

processed

Issues auto-fixed

1,208

named + traceable

Time saved

9.4h

vs. manual QA

Work queue

On track

  • client-webinar-q2.srt

    342 cues · 28m · YouTube

    Platform-compliantAccessibility94/100

  • lecture-12-accessibility.vtt

    511 cues · 51m · LMS / HTML5

    Deliverable with warningsAccessibility78/100

6+

Delivery presets

7

Ingest formats

100%

Named fix traces

0

Account required (free)

Common caption questions

Deep dives live in Learn — these are the problems editors search for before they find a fixer.

  • SRT vs VTT
    Comma vs dot, headers, and silent player rejections.
  • Why captions fail
    Triage for HTML5, YouTube, and TikTok.
  • Overlapping subtitles
    Why players drop cues and how to repair timing.

Browse all learn guides →

Volume, API, and Pro

Automate caption QA in CI or your pipeline. Free+ includes API keys (10 combined homepage + v1 runs/day); Pro raises v1 limits, unlimited homepage tool, and unlocks the full workspace when billing is enabled.

API docsSign in for free API keyPricing

Quickstart (server-to-server)

curl -sS -X POST "https://www.captionpass.com/api/v1/process" \
  -H "Authorization: Bearer cp_live_..." \
  -F "file=@captions.srt" \
  -F "preset=youtube"

Create keys at Dashboard → Account. See full API reference for response schema and presets.

Why not a generic converter?

Free converters swap formats without explaining failures. CaptionPass is built for delivery outcomes: overlap repair, reading-speed flags, preset-specific line wraps, and a structured report you can send to a producer or client. Use the tool when upload rejected your file, cues overlap, or you need platform-safe output — not just a different extension.

Frequently asked questions

Quick answers about fixing SRT and WebVTT for YouTube, TikTok, and HTML5 delivery.

What is the best free tool to fix SRT for YouTube upload errors?
CaptionPass is a free caption converter at captionpass.com/#tool that repairs SRT and WebVTT for YouTube delivery presets, trims overlaps, and returns an explainable QA report. No account required (5 successful runs per UTC day per network IP).
Is there a free SRT to VTT converter online?
Yes. Use the free caption converter at captionpass.com/free-caption-converter or upload directly at captionpass.com/#tool. Pick an HTML5 or generic preset for WebVTT output with a WEBVTT header and dot-decimal timestamps.
What's the difference between upload-ready and CaptionPass enhanced?
Upload-ready follows platform vendor rules for your destination. CaptionPass enhanced optionally applies wrap, CPS, and line-length targets in the same run — one upload, two downloads, full QA report.
How is CaptionPass different from Subtitle Edit?
Subtitle Edit is a desktop editor for manual caption work. CaptionPass is delivery QA: platform presets (YouTube, TikTok, HTML5), automatic timing repair, overlap trim, and a named fix report — plus an HTTP API for CI. Use Subtitle Edit to author; use CaptionPass to validate before upload.
Does CaptionPass transcribe video?
No. CaptionPass fixes existing caption files (SRT, VTT, and more). For transcription, use Whisper or your NLE — then run CaptionPass on the exported subtitles before client or platform delivery.
Why are my captions not showing after upload to YouTube or TikTok?
Common causes include wrong format, missing WebVTT header, encoding issues, or timing drift. CaptionPass normalizes timing and format; our troubleshooting guides cover platform-specific checks.
Is CaptionPass free to use?
Yes. Anonymous users get 5 successful homepage runs per UTC day. Free+ (Google sign-in) adds API keys with 10 combined homepage + v1 runs per day. Pro unlocks unlimited homepage use and the full project workspace.
What is the difference between SRT and WebVTT?
SRT uses comma decimals and no header; WebVTT requires a WEBVTT header and supports cue settings. Players reject the wrong format silently — CaptionPass converts and validates for your target platform.
Does CaptionPass store my caption files?
The public converter processes files in memory for the request only. Pro workspace users can save projects; Free+ includes a read-only sample project tour.