HermitFile Pro

Burn captions into a video

Takes a subtitle file you already have — an .srt or .vtt — and draws its text onto the matching video frames, timed to the clip. Runs entirely on this device. The original audio comes along unchanged if it's AAC.

Drop a video hereTap anywhere in this box
MP4, MOV, MKV, WebM — anything your browser can read. Any length: there is no upload, so there is no limit.

Nothing is uploaded. Open your browser’s Network tab while you convert — you will see the file go nowhere.

Subtitle file

Don’t have a subtitle file? Generate a rough one from this video’s own audio — a speech-recognition model runs on this device, the audio never leaves it, and you get a normal editable transcript to fix up before anything is burned in.

Download as .srt

Or, if you already have one:

Drop an .srt or .vtt file hereTap anywhere in this box

Caption style

The starting-frame preview updates as you adjust these.

What you'll get back

Worked out from this actual file and this actual browser, before anything is written.

Range and frame rate

Your video

No subtitle file? Generate one from the video's own audio

A speech-recognition model can run right here on this device to draft a transcript from the video's audio — the audio never leaves your browser to do it. You get back an ordinary editable transcript, not a black box: fix anything the model got wrong before it's burned in. Already have an .srt or .vtt file — from YouTube's own auto-captions, an editor's export, or one you wrote by hand? Skip the generator and drop that in instead; this tool draws its text onto the matching frames either way.

How the subtitle file is read

Both .srt and WebVTT (.vtt) are parsed into the same list of timed cues — a start time, an end time, and the text in between. Simple tags like <i> inside a cue are stripped, since the text is drawn onto the video picture rather than rendered as HTML. The parsing, cue lookup and word-wrap math were unit-tested standalone before being wired into this tool.

Why the audio sometimes doesn't survive

The video is genuinely re-encoded, because burning captions in means drawing new pixels on every frame that has one — there is no wrapper trick for that. Audio doesn't need to be, so it's copied across as compressed packets exactly like the site's other video tools do, provided it's AAC. Anything else would need a decoder and an encoder this tool doesn't carry, so it's dropped rather than silently guessed at, and the plan says so before you convert anything.

Nothing is uploaded

Reading the subtitle file, decoding, drawing the captions and video encoding all happen in this page. There is no server here to send the video to, and the page's security policy blocks any connection to anywhere but this site. Here is how that is enforced.

How to burn captions into a video

  1. Drop the video in, then drop in an .srt or .vtt subtitle file. Nothing is sent anywhere.
  2. Pick a position, text size and background style, and check the preview.
  3. Set the range, output size and frame rate, then press Convert and download.

All 39 HermitFile tools

Every one of them runs in your browser. Nothing you open is uploaded, and nothing is stored.

Show all tools

Image tools

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Video tools

MOV to MP4Turn an iPhone .mov into an .mp4 by swapping the wrapper, with the video copied across and nothing re-encoded. Trim a videoKeep the part you want. The clip is copied rather than re-encoded, so no quality is lost. Split into partsCut a long recording into pieces short enough to post, without re-encoding any of them. Rotate a videoChange the rotation flag a phone wrote instead of re-encoding the picture. Seconds, not minutes. Remove the soundDrop the audio track and copy every frame across untouched — same quality, same size. Video to MP3Convert a video’s sound to MP3, or lift the original audio out byte for byte with nothing re-encoded. Video to GIFPick a range, a frame rate and a size, and get an animated GIF back with nothing uploaded. Green screen swapSwap a green or blue screen for a solid colour with a live preview, no AI model and no watermark. Silence removerFinds the quiet stretches by listening to the audio and cuts them out, with a timeline showing every cut first. Blur pad to a new ratioFit a video into 9:16, 1:1 or another shape with a blurred background instead of black bars. Compress a videoAim at a Discord, email or WhatsApp limit — or your own — and get an MP4 checked afterwards, not just promised. Noise removerLearns your recording’s own background hiss or hum from a quiet stretch, then subtracts exactly that. Auto-reframeCrops into a new aspect ratio with the crop panning to follow the motion, instead of a fixed centre. CaptionsBurns an .srt or .vtt subtitle file into the video as styled, timed on-screen text. Beat syncFinds the beats in the clip's own audio and lands a flash or a zoom-punch on each one. Highlight finderScores a clip by loudness and movement, and ranks the best stretches to cut out, losslessly.

PDF tools

Merge PDFsJoin several PDFs into one, in the order you choose, and rotate pages losslessly. Split PDFPull out a page range, or break a document into one file per page. Compress a PDFShrink the pictures inside the file and leave the text selectable. Refuses to hand back a bigger file. PDF to imagesRender each page to a JPG or PNG at the resolution you choose. PDF to textPull the words out of a PDF and copy them or save a .txt file. Says so when a PDF is a scan. Remove a PDF passwordSave a copy that opens with no password, using the password you already know. Rotate PDF pagesTurn some pages or all of them, permanently, with no loss of quality. Remove PDF pagesName the pages you want gone and get everything else back as one document. Redact a PDFSearch every page for a name or a number, remove the text itself, then check the finished file. Images to PDFCombine photos into one PDF that lands under the KB limit the portal demands. Bank statement to CSVEvery transaction out of a statement PDF as a spreadsheet, and it checks its own total against the closing balance.