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無料オンライン画像形式変換ツール

形式を変換

画像フォーマット間での変換 - PNGからJPG、JPGからWebPへなど。バッチ変換、無限の画像。

ここに画像をドロップ！

または

JPG、PNG、WebP、GIF形式対応、一括処理可能

共有:

Why use this Free Online Bulk Image Converter

🔒 Private & secure — zero uploads, zero risk

Your images never leave your device. Period. All format conversion happens right inside your browser using client-side processing — no uploads, no servers, no snooping. Perfect for sensitive photos, business assets, design files, or personal memories you'd rather keep to yourself.

🔄 Convert multiple images to JPEG, PNG or WebP in one go

Why convert images one by one when you can process a whole batch at once? Turn PNG screenshots into JPEG, convert WebP images back to PNG, or create smaller WebP copies with one consistent output setting.

🎯 Three reliable output formats — everything most workflows need

Choose JPEG for photographs and broad compatibility, PNG for lossless graphics and transparency, or WebP for modern web compression. Keeping the output list focused makes batch conversion predictable across modern browsers.

🖼️ Preserve quality, strip the bloat

Converting formats doesn't have to mean visible quality loss. The quality control lets you balance file size and clarity, while PNG transparency is retained when the chosen output format supports it.

📦 Batch conversion done right

Upload a handful of images or dump an entire folder — we handle it. Convert 10, 50, or 100+ photos in one go, with the same output format applied consistently across the batch. Whether you're prepping product photos for a website or standardizing a mixed-format photo library, it all happens in seconds.

📥 Download however you want

Single image? Click download. Whole batch? Grab them all individually. Everything at once? Get a tidy ZIP file with one click. We built the download options to match how you actually work.

🆓 Actually free. No asterisks.

No watermarks. No daily limits. No "pro" paywall that unlocks the features you actually need. Unlimited images, unlimited conversion sessions, unlimited everything.

💻 Works everywhere, installs nowhere

No software to download, no account to create, no email to hand over. Open the site on Windows, Mac, Chromebook, or even your phone — drag, drop, convert, done. Works offline too once the page loads.

⚡ Instant — like, actually instant

No "processing" spinner that spins forever. No waiting for uploads or downloads. Format conversion happens in milliseconds because it's all happening on your machine.

🔄 Same batch, multiple tools

Converted your images but now need to compress or resize them? Your files stay loaded as you jump between tools. Convert first, then switch to the compressor or resizer — no need to re-upload the same images twice.

About this Free Online Bulk Image Converter

BulkPicResizer's Convert Image Tool is a free online bulk image converter that lets you change image formats without jumping through hoops. Whether you need to convert multiple images from PNG to JPEG for a website, turn WebP files into editable PNGs, or standardize an entire folder to a single format, this batch image format converter gets the job done in seconds.

Choose JPEG for photographs and compatibility, PNG for lossless graphics and transparency, or WebP for modern web compression. Animated source files are processed as a single still frame because browser canvas conversion does not preserve animation.

Key features:

✓ Batch conversion: Convert dozens of images to a single output format at once.
✓ Output formats: Batch convert images to JPEG, PNG or WebP.
✓ Flexible download: Download individual images, all images separately, or a single ZIP archive.
✓ Zero-upload architecture: 100% client-side processing means total privacy.
✓ No registration: Just open the page, drop your images, and start converting.

Frequently Asked Questions

Is this free online bulk image converter actually free?

No catch. It's 100% free — no watermarks, no hidden fees, no premium tier, no daily limits. You can convert as many images as you want, as many times as you want.

Do my images get uploaded to your server?

Absolutely not. This is a 100% client-side tool. Every format conversion happens locally inside your browser — we don't even have a server that could receive your images. Your files never leave your device.

What image formats do you support?

You can convert browser-supported images to JPEG, PNG or WebP. JPG, PNG and WebP are the most reliable inputs. GIF files can be opened, but animated GIFs are converted from a single still frame.

Can I convert multiple images at once?

Yes — that's kind of our thing. You can upload as many images as you want and convert the entire batch to a single output format at once. Each image will be converted individually.

What happens to transparent backgrounds when converting PNG to JPEG?

Great question. JPEG doesn't support transparency, so when you convert a PNG with transparent areas to JPEG, those areas need a background color. Our tool intelligently fills transparent areas with white by default, which works well for most use cases.

Does converting between formats reduce image quality?

It depends on the formats involved. PNG to PNG is lossless — zero quality loss. JPEG to JPEG or JPEG to WebP involves re-compression, which can introduce slight quality loss, though our engine minimizes it. For best results, always keep an original copy and convert from the highest quality source available.

Does this tool preserve GIF animations?

No. The converter uses browser canvas processing, which converts an animated GIF from a single still frame. Keep the original GIF if you need to preserve its animation.

Why would I convert WebP to PNG or JPEG?

WebP is a fantastic modern format for websites, but many older programs and apps still don't support it. If you've downloaded a WebP image and can't open it in your photo editor, converting it to PNG or JPEG solves the compatibility issue instantly.

Do I need to create an account or install anything?

Nope. This is a pure web tool that runs in any modern browser. Just visit the page, drop your images, and start converting. No sign-up forms, no software downloads, no email verification.

Can I convert and compress or resize at the same time?

While each tool is separate for simplicity, your batch of images stays loaded as you navigate between the Convert, Compress, and Resize tools. Convert first, then switch to another tool — no need to re-upload.

What's the best format for my use case?

Photos for websites or social media → JPEG. Logos, graphics, or images needing transparency → PNG. Modern web performance → WebP. Keep the original animated file when animation must be preserved.

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