Convert files on a Mac without uploading them, with nothing to install

What your Mac already does locally (and where it stops)

Before reaching for any website, it is worth knowing how much your Mac already converts on its own, fully offline. macOS Preview is the quiet workhorse here. Open a HEIC photo from your iPhone in Preview, choose File then Export, and you can save it as JPG, PNG, or TIFF without anything leaving your machine. Preview also exports between common image formats and can export or combine PDF pages by dragging thumbnails in the sidebar. Quick Look and the Finder's right-click Quick Actions cover a few more one-off tasks. Credit where it is due: for HEIC to JPG specifically, you may not need a website at all.

Where the built-ins stop is just as important. Preview does not convert audio at all, so an M4A voice memo, a FLAC music file, or a WAV recording is out of scope. It does not create or unpack ZIP and TAR archives as a format conversion. And while it can rasterize or recombine PDF pages, it has no concept of converting between many of the image and PDF format pairs people actually search for. macOS does ship more capable tools you can drive from Terminal (sips for images, the built-in zip and tar commands, even Audacity or ffmpeg if you install them), but those mean command lines or installs. The browser route on this page fills the gap with no install and no upload.

How hushvert converts on your Mac without uploading anything

Modern Mac browsers (Safari, Chrome, Firefox, Arc) can run real codecs compiled to WebAssembly. When you drop a file onto hushvert, your browser downloads the conversion engine once, then runs it on your file inside the page, on your Mac's own CPU. There is no upload step because there is no server doing the work. The only things fetched from the network are the page and the engine itself, never your file.

This is the core difference from a typical online converter. Most convenient web converters are server-based: your browser uploads the raw file bytes to a company's machine, the conversion runs there, and you download the result. That means a full copy of your file briefly lives on someone else's server. In March 2025 the FBI publicly warned that free online file-converter sites are a common vector for malware and data theft, precisely because so many route your files through servers you cannot see. hushvert answers that structurally rather than with a promise: for the client-side conversions described here, the file never reaches any server because the conversion happens in your browser tab.

The airplane-mode proof, on your Mac

You should not take a privacy claim on faith, and you do not have to. There are two ways to verify the no-upload behavior on a Mac in under a minute.

The airplane-mode test is the strongest. Load the converter page, then disconnect from the network: click the Wi-Fi icon in the macOS menu bar and turn Wi-Fi off (unplug Ethernet too if you use it). Now convert a file. It still works, because nothing needs to leave your machine. The /privacy-proof page has a built-in airplane-mode demo that walks through exactly this.

The Network tab is the second check. In Safari, enable the Develop menu (Safari, Settings, Advanced, Show Develop menu), then open Develop, Show Web Inspector, and click the Network tab; in Chrome or Firefox press Command-Option-I and choose Network. Convert a file and watch: you will see the engine load once, then no request carrying your file bytes. This is not just a one-time audit. A test in hushvert's suite asserts on every single code change that no network request may carry file bytes, so the no-upload guarantee cannot silently regress. The engine is open source under the MIT license (published as @hushvert/engine), so the behavior is auditable, not merely asserted.

Convert audio on your Mac, free and in the browser

Audio is the clearest case where Preview leaves you stranded and a no-upload browser converter earns its place. hushvert handles roughly 18 audio conversions client-side on your Mac, all running on an in-browser build of ffmpeg: MP3, WAV, FLAC, OGG, M4A, AAC, AIFF, and WMA in the common directions, including FLAC to MP3, WAV to MP3, M4A to MP3, and the reverse pairings. It can also extract an MP3 audio track from a video (MP4, MOV, MKV, WebM, AVI) entirely in the browser, which is handy when you only need the sound from a lecture or screen recording.

A precise note on quality, because we would rather you know it than discover it. Converting between lossless formats (WAV to FLAC, FLAC to WAV) preserves the audio samples exactly. Converting to a lossy target like MP3, OGG, or AAC genuinely re-encodes the audio, which is true of every MP3 encoder anywhere, not a hushvert quirk. If you are archiving a master, target WAV or FLAC; if you want a small, universally playable file, MP3 or M4A is the right tradeoff. Client-side audio conversion is unlimited and free with no account, with a per-file ceiling around 200 MB, which covers most files but can be exceeded by a very long uncompressed WAV. If you convert audio constantly, an offline desktop tool like Audacity or ffmpeg is a legitimate choice too; the browser route wins for a quick, no-install, no-upload one-off.

Images, archives, and PDF page tasks, all client-side on Mac

Beyond audio, several other no-install conversions run entirely in your Mac's browser. Images cover JPG, PNG, WebP, AVIF, GIF, BMP, TIFF, SVG, JXL, and ICO, plus decoding HEIC to JPG, PNG, WebP, or AVIF, so if you would rather not round-trip through Preview, or you want WebP or AVIF output that Preview does not offer, the browser handles it. Archives like ZIP, TAR, and TGZ are created and unpacked locally too.

For PDFs, hushvert covers specific page operations client-side: merging several PDFs into one (merge-pdf), rasterizing a PDF to JPG or PNG, extracting a PDF's text, and building a PDF from JPG, PNG, SVG, or text. Being honest about the edges matters here: there is no one-click PDF compressor and no PDF split, extract, or reorder tool, so do not expect those. (If you need to shrink a large PDF, you can rasterize it to JPG, compress, and rebuild a PDF from the images, but that is a lossy workaround, not a feature we oversell.) The first conversion in a browser session downloads the WebAssembly engine once, then caches it; after that, repeat conversions start instantly. Everything in this section keeps your files on your Mac.

The honest server-lane boundary

Some conversions a browser genuinely cannot do well, and hushvert is upfront about them rather than pretending. Converting office documents to PDF (DOCX, DOC, XLS, XLSX, PPT, PPTX, ODT, ODS, ODP, RTF, HTML), converting a PDF to an editable Word file (pdf-to-docx), and re-encoding very large video that exceeds the browser's memory ceiling run on a clearly-labeled server lane. That lane is always marked 'this one leaves your device' before you begin. On the server lane, inputs are deleted immediately after conversion and outputs within about an hour. Anonymous use is 2 server jobs per day, then a free email account raises it to 5 per day plus 150 MB per day; beyond that there is a 5 dollar Week Pass or credits that never expire, with no subscription.

One deliberate exception is worth calling out for Mac users: HEIC is never processed on the server, by design. HEIC relies on HEVC, which carries patent constraints, so HEIC decoding always stays client-side in your browser. The practical upshot is that the conversion most relevant to iPhone-on-Mac users, HEIC to JPG, PNG, WebP, or AVIF, is permanently a no-upload, browser-only operation. None of the client-side image, audio, archive, or PDF page tasks above ever touch the server lane.

Popular conversions that run on your Mac

• HEIC to JPG
• JPG to PNG
• PNG to WEBP
• WAV to MP3
• MP4 to MP3

Keep reading

• Convert HEIC to JPG without uploading
• Convert audio without uploading
• See the no-upload proof
• Private file converter: how it works

Common questions

Do I need to install anything to convert files on my Mac this way?

No. hushvert runs in your browser (Safari, Chrome, Firefox, Arc), so there is nothing to download or install. The first conversion in a session fetches a small WebAssembly engine once and caches it; after that, conversions start instantly. For HEIC to JPG specifically, your Mac's built-in Preview app can also export locally with no website needed, so we will happily point you there when it is the simpler path.

Is hushvert different from Mac Preview, and when should I use each?

Preview is excellent and fully offline for what it covers: exporting HEIC and common images to JPG, PNG, or TIFF, and combining or rearranging PDF pages by dragging thumbnails. Use Preview when it already does the job. Use hushvert in the browser for things Preview cannot do at all, such as converting audio (MP3, WAV, FLAC, OGG, M4A), creating or unpacking ZIP and TAR archives, outputting WebP or AVIF, or PDF page tasks like merging PDFs and converting a PDF to JPG or PNG. Both keep your files on your Mac.

How do I prove the file is not being uploaded from my Mac?

Two checks. The strongest is airplane mode: load the converter, turn off Wi-Fi from the macOS menu bar (and unplug Ethernet), then convert. It still works because nothing leaves your machine. The /privacy-proof page has a built-in airplane-mode demo. You can also open your browser's Network tab (Develop, Show Web Inspector in Safari, or Command-Option-I in Chrome and Firefox) and watch the conversion: the engine loads once, then no request carries your file bytes. A test asserts this on every code change, and the engine is open source under MIT.

Can I convert audio on my Mac for free without uploading it?

Yes. hushvert converts roughly 18 audio pairs client-side on your Mac using an in-browser build of ffmpeg, covering MP3, WAV, FLAC, OGG, M4A, AAC, AIFF, and WMA, plus extracting MP3 audio from MP4, MOV, MKV, WebM, and AVI video. It is unlimited and free with no account, with a per-file ceiling around 200 MB. Lossless-to-lossless conversions like WAV to FLAC preserve samples exactly; converting to a lossy target like MP3 genuinely re-encodes, which is true of any MP3 encoder.

Are there any conversions that do leave my Mac?

Yes, and hushvert labels them clearly before you start. Office documents to PDF (DOCX, XLSX, PPTX, and similar), PDF to Word, and very large video that exceeds the browser's memory ceiling run on a server lane marked 'this one leaves your device.' On that lane, inputs are deleted immediately after conversion and outputs within about an hour. HEIC is never sent to the server for patent reasons, so HEIC conversion always stays in your browser. Image, audio, archive, and PDF page tasks described here are all client-side and never use the server lane.

Can hushvert compress or split a PDF on my Mac?

Not as a one-click feature, and we will not pretend otherwise. hushvert does merge multiple PDFs into one, rasterize a PDF to JPG or PNG, extract a PDF's text, and build a PDF from images or text, all in your browser. There is no dedicated PDF compressor and no PDF split, extract, or reorder tool. To shrink a large PDF you could rasterize it to JPG, compress, and rebuild a PDF, but that is a lossy workaround rather than a real compression feature.