Burn one shared SRT subtitle file permanently into a whole batch of videos with font-size and bottom/top/middle position control. Course creators hard-sub 20 lessons for platforms that ignore caption files — FFmpeg WASM, 2 free batches a day. Videos never leave your device — compression and conversion run locally in your browser with FFmpeg WASM.
Runs on FFmpeg
Content reviewed October 2026 · About Toolzum
Compress multiple videos with one shared CRF setting (18 high quality, 23 default, 28 smaller, 35 maximum) encoded libx264 medium preset with 128k AAC audio. Studios batch 20 daily uploads at CRF 28 — local FFmpeg WASM, 2 free batches a day.
Burn text watermarks into a video with 5 position presets (bottom-right default, fixed 24px white on semi-transparent black box). Brand one clip at a time — local FFmpeg work, unlimited saves.
Hit exact file-size targets (10/25/50/100 MB, default 50) across video batches for email and messaging caps. Teams fit 15 clips under Gmail's 25 MB wall — local FFmpeg WASM, 2 free batches a day.
Strip or swap backgrounds on whole photo batches with color-key sampling and tolerance control. Sellers turn 40 supplier shots into clean white listings in one run — local Canvas work, 2 free batches a day.
Bind hundreds of JPG, PNG, or WebP images into one multi-page PDF with page size, orientation, and fit control. Agents compile 80 property photos into a brochure — local jsPDF work, 2 free batches a day.
Burn-in when platforms strip caption files (WhatsApp, Instagram, some LMS players) — text becomes pixels, always visible. Sidecar SRT when viewers need toggle and translation. A 20-lesson course burns one styled set for social and ships SRT for YouTube.
One uploaded SRT burns into every video in the batch (force_style FontSize plus Alignment 2 bottom, 8 top, or 5 middle) — there is no per-file auto-pairing. Mismatched timing burns permanently wrong, so spot-check one video's first and last minute before running all 20.
Bold default sans at size 18+ (raise it for phones), bottom-center with safe margins: desktop-readable small text shrinks to illegible on 6-inch screens. There is no font-face or color picker — size and position only.
No — burning runs locally in your browser with FFmpeg WASM; files never leave your device. Only final saves count against Pro downloads.
Subtitle Generator
Create SRT/VTT subtitles manually by typing or dictating text with live timestamp capture. No automatic transcription — you provide the text.
Subtitle Translator
Translate pasted SRT or VTT subtitle text into 9 languages (Spanish, French, German, Japanese, Chinese, Hindi, Portuguese, Russian, Arabic) while preserving every timestamp — AI-powered with your own API key, text never stored.
Bulk Subtitle Time-Shifter
Shift subtitle timing by ±milliseconds with pasted SRT/VTT text and instant before/after comparison. Localizers fix a 2.5s broadcast delay — paste, shift, copy or download, all local.