Drop two images of the same scene. Drag the handle to reveal the difference. Save as a single side-by-side image.
Before / after slider delivers in-browser image processing using HTML5 Canvas and the WebCodecs API, built for photographers, designers, marketers, social media managers, e-commerce sellers, and casual users. It is part of the Toolvana family — a curated collection of 190+ free, privacy-respecting browser tools built and maintained by Aravind Labs. The aim is simple: replace expensive SaaS subscriptions and surveillance-heavy web tools with something fast, clean, and trustworthy.
Drop two images, get an interactive side-by-side reveal slider. Perfect for showing edits/transformations. Under the hood, the tool is powered by Canvas 2D, OffscreenCanvas, and modern image codecs like WebP and AVIF. The result is something that feels like a native desktop app: instant feedback, no loading spinners after the first paint, and full control over your data.
The web is full of "free" tools that ransom your file in exchange for an email address, plant trackers on your browser, or sell your data to "advertising partners" buried in a 40-page privacy policy. Before / after slider takes the opposite stance: Images are decoded into a Canvas element on your device. No upload happens — even the largest 50 MB photo stays in your browser memory.
For users who handle anything sensitive — legal contracts, medical PDFs, ID documents, financial spreadsheets, private journals — this difference is not academic. Once a file leaves your device, you have no idea where it goes, who reads it, how long it is kept, or what happens during a data breach. With Before / after slider, the answer is permanent: nothing leaves, nothing to leak.
When you open the page, your browser downloads a small JavaScript bundle that contains the tool logic. Once loaded, every action — file processing, computation, rendering — happens locally using your CPU and GPU. The browser exposes capabilities like Canvas 2D, Web Audio, Web Crypto, WebAssembly, and WebCodecs that, combined, are enough to do what desktop apps used to require.
This architecture has three implications: (1) privacy by design, since there is nowhere for data to leak; (2) speed, since there is no network round-trip; (3) offline capability, since once loaded, the tool keeps working without internet. The trade-off is that very heavy compute (training AI models, transcoding multi-hour videos) is still better-suited to native software — though even there, browser capabilities are catching up fast.
Before / after slider helps with cropping for Instagram square, resizing for TikTok 9:16, compressing reels under WhatsApp 16 MB limit, adding watermarks before posting.
Before / after slider helps with preparing product photos for Amazon, Flipkart, Meesho — all platforms have strict dimension requirements that this tool handles in one click.
Before / after slider helps with converting between PNG, JPG, WebP, AVIF; generating multiple favicon sizes; preparing assets for retina displays.
Before / after slider helps with compressing hero images to improve Core Web Vitals, generating Open Graph 1200x630 images, exporting featured images for SEO.
Before / after slider helps with shrinking phone photos to email-friendly sizes, removing metadata before sharing, creating memes, generating profile pictures.
Yes — Toolvana is free with no signup, no trial expiration, and no hidden limits. The site is supported by lightweight, non-intrusive ads (and donations from grateful users). You will never be asked to upgrade for a premium tier or hit a "5 uses left" wall.
Images are decoded into a Canvas element on your device. No upload happens — even the largest 50 MB photo stays in your browser memory. You can verify this yourself by opening DevTools → Network tab and watching for outbound requests while you use the tool.
After the first load, the JavaScript and assets are cached by your browser. Most operations work offline — only tools that explicitly call out external AI or API services require a connection. The browser registers a service worker so the page loads without a network round-trip on repeat visits.
Yes. The interface is fully responsive and supports touch input. We test on iOS Safari, Chrome on Android, and major desktop browsers (Chrome, Firefox, Safari, Edge) — last verified in May 2026.
Yes. Toolvana tools are usable for personal, educational, and commercial work. Output (generated images, processed documents, etc.) is owned by you under the licenses of the underlying libraries. Pollinations-generated images carry no commercial restrictions for typical usage.
Most paid tools (Adobe Acrobat, Canva Pro, SmallPDF Premium, Grammarly Premium) charge ₹500-3000/month for similar functionality. Toolvana provides the same core capabilities free, with one trade-off: heavy compute (AI image generation) is rate-limited at peak times. For ~95% of day-to-day use, the experience is identical or better.
Because everything runs in your browser, there is no upload time, no queue, no server cold-start. A 5 MB file that would take 8 seconds to upload to a competitor finishes processing here in under 2 seconds — limited only by your CPU.
Browser-only tools have no recovery state — if the tab crashes during a long operation, you start over. We mitigate this by chunking large operations and reporting progress, so you know how far along you are. For mission-critical tasks, always keep a backup of the source file.
Toolvana has 190+ tools across categories. Some related ones you might find useful:
Toolvana is a free, ad-supported, privacy-first multi-tool web app built and maintained by Aravind Labs. The site has no paid tier, no enterprise upsell, and no premium gating — every tool is fully functional for every visitor. Light ads keep the lights on; that is it. If a tool ever feels broken, slow, or sketchy, the source is open in your browser's DevTools — and you can drop a note via the contact page on the parent site.
Last updated: May 2026. Tools are continuously added based on what real users ask for. If you have a request, open an issue on the AravindLabs site or reach out via the contact page.