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Online DICOM viewer vs app: when a browser isn’t enough

Browser viewers such as IMAIOS, DocOrbit, DicomViewer.net and OHIF open DICOM without installing anything, and several of them process the files locally in the browser. On an iPhone or iPad they struggle with discs, ZIP/RAR archives and large CBCT volumes — an app like Ossidex handles those offline. Ossidex itself is an app, not a website: there is no online Ossidex viewer.

By the Ossidex team · How we write and check these pages · Updated

Download on the App StoreFree to download · iPhone & iPad · iOS 17+
Studies imported into the Ossidex app on iPhone, stored on the device

Online DICOM viewers compared

ViewerPriceWhere your files goGood for
IMAIOS DICOM Viewer (web)Free for personal and non-commercial useProcessed locally in the browser (“your files are not uploaded”)Viewing a study on any computer; same viewer on iOS and Android
DocOrbit DICOM viewerFree, no accountParsed and rendered locally in the browserSingle files, folders and ZIPs, with measurements
DicomViewer.netFreeProcessed locally (“nothing is uploaded”); built on OHIFQuick look on Mac, Windows or Linux
Medicai free online viewerFree, no registrationProcessed in the browser, not uploadedA quick look before sharing
OHIF ViewerFree, open source (MIT)Reads from your organisation’s DICOMweb serverHospitals and research groups with their own archive
PostDICOMPaid plans, 7-day trialUploaded to cloud storage (Microsoft Azure regions)Storing and sharing studies with a team
DICOM LibraryFree, for education and researchAnonymised in the browser, then uploaded to its serverSharing teaching cases publicly

As described on each service’s own site, checked September 27, 2026. “Processed locally” is the vendor’s statement; we did not audit their code.

When a browser viewer is the better choice

  • You are at a computer you do not own and cannot install software — a browser viewer that works locally leaves nothing behind.
  • You need a quick look at a few files on Windows, Mac, Linux or a Chromebook.
  • Your hospital already runs OHIF or a web PACS — use it; it is connected to the archive.
  • You need to share with a team and a cloud platform is approved by your organisation.

When an app is the better choice

  • The scan is on your iPhone or iPad. Mobile browsers cannot pick a whole disc folder the way a desktop browser can, and memory limits in mobile Safari make large volumes unreliable.
  • It arrived as a RAR, 7z or ISO, or as a ZIP inside a ZIP — Ossidex unpacks these on the device; most browser viewers expect plain DICOM or ZIP.
  • It is a large CBCT or multi-series study. A native app decodes JPEG 2000 and HTJ2K with the device’s CPU and GPU and caches the volume for MPR and 3D.
  • You need it offline — in a clinic basement, on a plane, or at the chair with poor reception. An imported study opens without a connection.
  • You open studies every day. A library of patients and studies on the device beats re-opening files in a browser tab.

Open CT, dental CBCT and MRI from any scanner on the iPhone or iPad you already carry — no laptop needed.

Privacy: what “upload” means for a medical scan

A DICOM file carries the patient’s name, birth date, ID and study details in its header. Three models exist:

ModelExampleWhat leaves your device
Local in the browserIMAIOS web, DocOrbit, DicomViewer.netNothing, according to the vendor — the page code runs on your computer
Cloud uploadPostDICOM, DICOM Library, cloud PACSThe study (anonymised first in some services) is stored on the provider’s servers
Native app on the deviceOssidexNothing — images are processed on the iPhone or iPad and not uploaded to Ossidex servers

Before opening a patient’s scan in any online tool, check its privacy policy, whether it stores files and where, and whether your organisation allows it. If you only need to share a picture, an anonymised export or a PDF report avoids sending the full study.

Opening the same study in Ossidex

  1. Install Ossidex. Free on the App Store for iPhone and iPad (iOS/iPadOS 17 or later). No account.
  2. Bring the files. Save the ZIP or folder to Files, plug in a USB-C stick, or copy the share link you would have opened in the browser.
  3. Import. Tap + and choose the folder, archive or link. Archives are unpacked and every series is listed.
  4. View offline. Scroll in 2D and measure for free; MPR, 3D and the dental arch are Pro. The study stays on the device.

Frequently asked questions

Is there an online version of Ossidex?

No. Ossidex is an app for iPhone and iPad; studies are processed on the device. For a computer, use a desktop or browser viewer.

Are online DICOM viewers safe?

Some process files locally in the browser and upload nothing; others upload the study to their servers. Read the service’s privacy statement before opening patient data, and prefer anonymised copies.

Can I open a DICOM CD in an online viewer?

On a computer with a disc drive, yes: many browser viewers accept a folder or ZIP. On an iPhone or iPad there is no disc drive — copy the disc once or ask for a link, then import it in an app.

Do online viewers work on an iPad?

Many open in Safari, but picking a disc folder, unpacking RAR/7z and handling large volumes are limited in mobile browsers. A native app is more reliable for those.

Sources

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