Subtitle Composer

Free plan Linux

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What Subtitle Composer is

Subtitle Composer is a free, open-source subtitle editor for Linux, with text-based tools for basic and advanced editing. It opens and saves formats such as SRT, MicroDVD, SSA/ASS, MPlayer, TMPlayer, and YouTube captions, and can open or OCR several graphics subtitle formats. Users can preview subtitles in an integrated video player or over an audio waveform, select an audio stream, and demux subtitle streams from video files. Editing tools include synchronization, time shifting and scaling, frame-rate conversion, joining and splitting files, side-by-side translations, styling, spell checking, and timing-error detection. Speech recognition from audio or video files uses PocketSphinx. Translation is supported; version 0.8.0 release notes list DeepL and Google Cloud engines. Linux installation options include Discover or another AppStream store, distribution package managers, Flathub, an x86_64 AppImage, and source downloads. Version 0.8.2 requires FFmpeg 5.1.5 or later. The product page lists GPL-2.0+ licensing and links to KDE's help forum and bug reporting.

Who it suits

Subtitle Composer suits Linux users who need to edit, synchronize, translate, or review subtitle files. Its range of text formats and editing tools can serve both basic and advanced subtitle work.

What it does well

Free and open source
Supports numerous text subtitle formats
Offers speech recognition using PocketSphinx
Includes synchronization and timing-error detection
Multiple Linux installation options

What to know first

Linux platform only
Requires FFmpeg 5.1.5 or later
Python and Ruby support were removed from scripting

Limits

Subtitle Composer is listed as free, with no paid plans or usage limits stated. The 0.8.2 release requires FFmpeg version 5.1.5 or later.

Plans

Plan	Billed and limits	Price
Subtitle Composer	Free · No paid plans or usage limits stated	Free

As apps.kde.org lists them, read 3 Oct 2026. The maker's own page has the final word.

Getting started

Visit https://apps.kde.org/subtitlecomposer/.
Install on Linux through Discover or another AppStream store, a distribution package manager, or Flathub.
Alternatively, download the x86_64 AppImage or source.
Ensure FFmpeg version 5.1.5 or later is available.

Verdict

Subtitle Composer offers extensive subtitle editing, preview, and translation tools at no listed cost. Linux users should account for its FFmpeg requirement and the scripting changes noted in its release information.

Questions

Is Subtitle Composer free?

Yes. The listed plan is free, and it is open-source software under GPL-2.0+.

Which platforms does it support?

The listed platform is Linux. Installation options include Discover or another AppStream store, distribution package managers, Flathub, an x86_64 AppImage and source downloads.

Which subtitle formats can it handle?

It opens and saves SRT, MicroDVD, SSA/ASS, MPlayer, TMPlayer and YouTube captions. It can also open or OCR several graphics subtitle formats.

Does it support subtitle translation?

Yes. Release notes for version 0.8.0 describe DeepL and Google Cloud translation engines.

Does it support speech recognition?

Yes. It supports recognition from audio or video files using PocketSphinx.

What does it require?

The 0.8.2 release announcement says Subtitle Composer requires FFmpeg version 5.1.5 or later.

Facts from Subtitle Composer's own pages

Auto-captioning: Yes · apps.kde.org, 20 Sept 2026
Download: The product page lists Linux installation through Discover or another AppStream store, distribution package managers, and Flathub, plus an x86_64 AppImage and source downloads. · apps.kde.org, 3 Oct 2026
Editing tools: Features include synchronization, time shifting and scaling, frame-rate conversion, joining and splitting files, side-by-side translations, text styling, spell checking, and timing-error detection. · apps.kde.org, 3 Oct 2026
Free plan: Yes · apps.kde.org, 20 Sept 2026
Legal entity: KDE says its legal and financial matters are represented by KDE e.V., a registered non-profit in Germany. · kde.org, 3 Oct 2026
License: The product page lists the license as GPL-2.0+. · apps.kde.org, 3 Oct 2026
Maker: KDE describes itself as an international community developing free, open-source software and says it has done so since 1996. · kde.org, 3 Oct 2026
Runtime requirement: The 0.8.2 release announcement says Subtitle Composer requires FFmpeg version 5.1.5 or later. · subtitlecomposer.kde.org, 3 Oct 2026
Scripting: The feature list describes scripting through languages supported by Kross; the 0.8.0 release notes say Kross was replaced with QJSEngine and Python and Ruby support were removed. · apps.kde.org, 3 Oct 2026
Security and privacy: KDE's software privacy policy says KDE software generally does not transmit information from end-user devices except after an explicit user action, and says any telemetry is opt-in and disabled by default where present. · kde.org, 3 Oct 2026
Speaker labels: Yes · apps.kde.org, 20 Sept 2026
Speech recognition: The application supports speech recognition from audio or video files using PocketSphinx. · apps.kde.org, 3 Oct 2026
SRT export: Yes · apps.kde.org, 20 Sept 2026
Subtitle formats: It opens and saves text formats including SRT, MicroDVD, SSA/ASS, MPlayer, TMPlayer, and YouTube captions, and can open or OCR several graphics subtitle formats. · apps.kde.org, 3 Oct 2026
Support: The product page links to KDE's Discuss help forum and provides a bug-report link. · apps.kde.org, 3 Oct 2026
Subtitle translation: Yes · apps.kde.org, 20 Sept 2026
Translation engines: The 0.8.0 release notes say DeepL and Google Cloud translation engines were added. · apps.kde.org, 3 Oct 2026
Video and audio: It can demux subtitle streams from video files and preview subtitles in an integrated video player or on an audio waveform, with audio stream selection. · apps.kde.org, 3 Oct 2026
VTT export: Yes · apps.kde.org, 20 Sept 2026
What it does: Subtitle Composer is an open-source, text-based subtitle editor for basic and advanced editing. · apps.kde.org, 3 Oct 2026