feat(posts): add "Bulk Image Converter"

Post: 2026-08-21-bulk-image-converter.md

Author: remarkablemark

_posts/2026/2026-08-21-bulk-image-converter.md

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+---
+layout: post
+title: Bulk Image Converter
+date: 2026-08-21 14:34:37
+excerpt: How I built a browser-based bulk image converter that converts multiple images at once — no uploads, no server, fully client-side.
+categories: image react javascript canvas browser website
+---
+
+How I built a [bulk image converter](https://remarkablemark.org/bulk-image-converter/) that converts multiple images in your browser.
+
+## Motivation
+
+Most bulk image converters online require uploading files to a server. That raises privacy concerns, especially for sensitive images. Bandwidth costs add up for large batches and free services often have ads or limit file counts.
+
+**Bulk Image Converter** sidesteps all of that by processing images entirely in the browser using the HTML Canvas API.
+
+## Features
+
+- **Drag-and-drop or click to upload** multiple images at once.
+- **Batch conversion** to WebP, JPEG, PNG, or AVIF.
+- **Quality control** with a slider for lossy formats (WebP, JPEG, AVIF).
+- **ZIP download** of all converted images in one click.
+- **Per-file status** tracking (pending, converting, done, error).
+
+## How It Works
+
+1. **Upload images** — drag-and-drop or click to browse.
+2. **Select a format** — select from WebP (default), JPEG, PNG, or AVIF.
+3. **Adjust quality** — a slider appears for lossy formats (PNG is always lossless).
+4. **Convert & download** — all images are converted in parallel and archived into a single ZIP file.
+
+## Technical Decisions
+
+### Canvas API
+
+Each image is loaded into an `HTMLImageElement`, drawn to a `HTMLCanvasElement`, and exported via `canvas.toBlob()` with the target MIME type and quality.
+
+### JSZip
+
+The converted blobs are bundled into a ZIP file using [JSZip](https://stuk.github.io/jszip/). The ZIP is generated in memory and downloaded via a temporary `<a>` element with `URL.createObjectURL()`.
+
+## Try It
+
+You can try the [Bulk Image Converter](https://remarkablemark.org/bulk-image-converter/) or check out the [source code](https://github.com/remarkablemark/bulk-image-converter).