SmartSub

Overview

SmartSub is a free, open-source desktop app for turning video speech into edited, translated, and rendered subtitles, with optional dubbing. It is best suited to people who want a broad media workflow on their own computer, rather than a browser-based caption editor. Its strongest case is the combination of local processing and unlimited local use; cloud transcription is a poor fit for sensitive audio.

Key features

SmartSub includes whisper.cpp and lets users select faster-whisper, FunASR, Qwen3-ASR, or FireRedASR for transcription. That choice is useful for workflows that need different engines, while local models keep files on-device during processing. Cloud transcription instead uploads audio to the configured provider endpoint, so the maker advises against it for sensitive content.

Translation spans 20 services, including a built-in free option and integrations such as DeepSeek, Gemini, and Ollama. In the proofreading workspace, video-synced editing, undo and redo, search and replace, and AI proofreading help users revise text in context rather than treating the transcript as a separate document.

For dubbed output, SmartSub can synthesize speech from subtitle lines, align it to the timeline, and clone voices using ZipVoice, Volcengine, or ElevenLabs. Rendering supports burned-in captions or soft-subtitle packaging, style previews, and a dubbed audio track. Caption styling, brand presets, and speaker identification add control over presentation, though the app’s broad feature set will matter most to users who need more than basic transcription and export.

SmartSub also downloads videos from links including Bilibili and YouTube through yt-dlp and lux, supporting more than 1,800 sites. The repository README describes MCP and CLI automation with 111 tools and commands for media workflows, which may suit repeatable or integrated production tasks. GPU acceleration options include CUDA for NVIDIA and Vulkan for AMD or Intel on Windows and Linux, and Core ML or Metal on Apple-silicon Macs.

Pricing

Free: free. The plan includes local transcription, translation, text-to-speech, and subtitle rendering, with no local usage limits. That makes it a strong fit for individual creators who can run the desktop app and keep processing local. Optional cloud services are paid, so using them changes the cost equation; local use is the way to retain the no-cost advantage. There is no free trial because the plan itself is free.

The project is MIT-licensed. Help and participation are directed through documentation, FAQs, community groups, GitHub issues, and pull requests.

Platforms

SmartSub has desktop builds for Windows, macOS, and Linux. Packages cover Windows x64, macOS arm64 and x64, and Linux x64. That is a good fit for desktop workflows across those systems, but not for someone seeking an Android, iOS, or web app.

Who it's for

Choose SmartSub if you want one desktop workflow for transcription, translation, subtitle correction, dubbing, and rendering, especially when local processing and uncapped local use matter. It is less compelling for simple captioning needs, cloud-first editing, or work that must happen in a browser or on mobile. Anyone handling sensitive audio should keep transcription local rather than use a cloud provider.

Pros and cons

• Pros: No local usage limits on the free plan, making repeated subtitle work possible without a local quota.
• Pros: Local models keep files on the computer during local processing, a useful privacy distinction from cloud transcription.
• Pros: Transcription, translation, proofreading, dubbing, and rendering in one app can reduce handoffs between tools.
• Cons: Cloud transcription uploads audio to the configured provider, making it unsuitable for sensitive content.
• Cons: It is a desktop-only choice, with no mobile or web platform in the supported builds.
• Cons: Cloud services are optional paid services, so cloud-dependent use is not covered by the free local plan.

Alternatives

For a broader shortlist, browse AI Video Caption Generators.

• Whisper is a simpler choice if you want MIT-licensed code and model weights installed locally with Python and ffmpeg, rather than SmartSub’s integrated subtitle editing, dubbing, and rendering workflow.
• VideoCaptioner is another free, open-source option if you want an MIT-licensed alternative for captioning.
• Captions may suit users who need Android, iOS, or web access and AI video creation; its Max plan is $24.99 a month and includes 500 credits per month, AI Edit styles, AI video creation, and digital twins or custom AI actors.
• SRTGen is a web or API option for a limited free localization test drive, with SRT, VTT, and TXT export, a 5-minute screen-recording limit, and 2 GB storage.
• CaptionRoom is worth considering for a web-accessible editor with a free tier that includes manual captions in two styles, exports up to 1080p plus .srt, and no watermark.
• Moonshot offers a web-based free tier with 5 minutes to upload and preview ever, 15 AI credits, 109 transcription languages, and no video export.
• GetCaptions is a web or API alternative whose free Starter plan allows 60 minutes of transcription per month, videos up to 5 minutes, 720p export, and three projects.
• Fluen AI Subtitle Generator is another option to compare for its free allowance of three files up to 90 minutes each.

Verdict

SmartSub is a strong choice for creators who want a free desktop suite for the full subtitle workflow and can keep processing local. Its breadth, uncapped local use, and rendering options are the reasons to choose it; look elsewhere if you need browser or mobile access, or if your workflow depends on cloud transcription for sensitive content.