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Free tools for video editors & designers

In-browser utilities for video editors, motion designers, and anyone working with subtitles or images. Format converters, editors, calculators — all free, no signup, no file uploaded anywhere. Built and maintained by the Subflow team.

Subtitle file-format converters

SRT to VTT Converter

Convert SubRip (.srt) to WebVTT (.vtt) for HTML5 video, YouTube, and browser <track> elements.

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VTT to SRT Converter

Convert WebVTT (.vtt) back to SubRip (.srt) for Premiere Pro, DaVinci Resolve, VLC, and social-media uploads.

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ASS to SRT Converter

Convert Advanced SubStation Alpha (.ass) anime / fansub subtitles to plain .srt for media players and editors.

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SRT to TXT Converter

Extract a clean, paste-ready transcript from an .srt — indices, timing, and inline tags stripped.

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TXT to SRT Converter

Turn a plain-text transcript into a timed .srt file. Timing estimated from reading speed (15 cps).

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SRT to PDF Converter

Render an .srt as a printable A4 PDF transcript with timestamps and page numbers.

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Subtitle editors

Subtitle Synchronizer

Shift every cue in an .srt file forward or backward by a fixed number of seconds. Fixes constant-offset sync problems.

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Subtitle generators

SRT Generator

Compose a .srt subtitle file from scratch — one cue per row, type text + start/end times, download as .srt.

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Image-format converters

PNG to JPG Converter

Convert PNG to JPG (JPEG) in your browser. Tune quality, flatten transparency on a custom background color.

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JPG to PNG Converter

Convert JPG (JPEG) to lossless PNG. Useful for re-editing, screenshots, transparency overlays.

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PNG to WebP Converter

Convert PNG to WebP for smaller files at the same visual quality. Web-optimized format with transparency support.

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WebP to PNG Converter

Convert WebP back to PNG for editors that don't read WebP natively (older Photoshop, AE versions, print tools).

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PNG to AVIF Converter

Convert PNG to AVIF — the modern image format with the best compression for web. Tune quality, keep transparency.

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PNG to BMP Converter

Convert PNG to BMP (24-bit bitmap). For legacy Windows software, embedded systems, and uncompressed pipelines.

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Image editors

Image Resizer

Resize PNG, JPG, or WebP images. Lock aspect ratio, set width or height in pixels, downscale or upscale.

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Image Cropper

Crop images to a specific area or aspect ratio (1:1, 16:9, 9:16, 4:5). Free-form or fixed-ratio.

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Image Compressor

Compress JPG and WebP images by tuning quality. See before/after file sizes side by side.

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Add Text to Image

Overlay text on an image — pick font size, color, position. For thumbnails, social posts, quick captions.

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Add Watermark to Image

Stamp a watermark image (logo, signature) onto a photo. Tune opacity, scale, position.

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Image utilities

Color Palette Extractor

Pull a 5–10 color palette from any image. Get hex / RGB values for design and motion-graphics work.

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Image to Base64 Converter

Convert an image to a Base64 data URI for inlining in CSS, HTML, JSON, or APIs that don't accept file uploads.

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QR Code Generator

Generate a QR code from a URL or text. Download as PNG or SVG, tune size and error correction.

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Calculators

Aspect Ratio Calculator

Compute the missing dimension when you know the aspect ratio. Useful for resizing video, image, banner crops.

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Resolution Calculator

Calculate pixel counts, megapixels, scale ratios, and storage estimates between resolutions (HD, 4K, 8K).

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Reference & cheat sheets

Frame Rate Cheat Sheet

Reference table: 23.976, 24, 25, 29.97, 30, 50, 59.94, 60 fps — when to use which, drop-frame vs non-drop.

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Social Media Video Specs

Up-to-date specs for TikTok, Reels, YouTube Shorts, X, LinkedIn — resolution, aspect ratio, duration, bitrate.

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Why we built these

Subflow makes a captions plugin for After Effects. When we started writing the plugin we kept hitting subtitle-format conversions and edits we wanted to do quickly, away from the NLE timeline. Most online tools either gate the conversion behind a signup, upload files to their server, or run on stale JavaScript that breaks on modern subtitle quirks.

So we're publishing the converters and editors we use internally. All of them run client-side — the conversion logic is plain JavaScript that loads with the page and never sends your file anywhere. You can verify this in your browser's network tab while converting: no upload request is made.

Catalog last updated · 26 tools live

Working in After Effects?

Subflow generates captions directly inside After Effects — frame-accurate timing, broadcast-grade positioning, no exporting and re-importing.

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