Frequently asked questions.
Expand any topic to learn how iStrx handles formats, performance, privacy, and workflow details.
Which formats can I import?
JPEG, PNG, WebP, and HEIC. HEIC is decoded locally with a lazy-loaded WASM module.
Can iStrx encode HEIC?
No. iStrx decodes HEIC inputs, then exports JPEG or WebP (AVIF appears only if your browser supports native encoding). You can also add text or logo watermarks in bulk to every exported image.
What output formats are available?
Keep original, JPEG, or WebP on all modern browsers. AVIF appears when the browser exposes encoding support.
How should I choose quality?
Start around 75-85 for JPEG/WebP. Lower values shrink file size, higher values preserve detail. Preview a few results before large runs.
How do I avoid upscaling?
Enable Don't upscale. iStrx never enlarges images beyond their original size when this is toggled on.
Why is batch rename off by default?
To preserve your original filenames. Enable rename and use patterns like image-{counter:000}
when you need organised outputs.
Any performance tips for large batches?
Stick with the default worker count, keep the tab focused, and close heavy apps if you see slowdowns. Pause and resume is always safe.
What keyboard shortcuts are available?
Space to start or pause, Delete to clear the queue.
Does it work offline?
Yes. After the first load the app shell is cached for offline use. Your images and outputs are never cached.
What about privacy and data?
Everything runs locally. Files never upload. Optional analytics, if enabled, collect aggregate page metrics only.
Need more help?
Reach out at hello@istrx.app or open the tool and tap the in-app help overlay.
Ready to try the answers in action?
Drop a batch into iStrx and see HEIC decode, presets, and worker concurrency run entirely in your browser.