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Slim
NewSlim v2: the redesign

The web viewer for DICOM slide microscopy

Slim opens whole slide images, annotations and AI results straight from any DICOMweb archive. Open source, zero footprint, and built on the DICOM standard from the first pixel.

Open the demoRun your ownGitHub
Developed and supported byNational Cancer Institute Imaging Data Commons

Drag to compare the dark and light themes

The worklist, filtered to studies that contain derived objects. (dark theme)

The worklist, filtered to studies that contain derived objects.

slide series in IDC open in Slim
76,000+
DICOM object types supported
7
install: runs in the browser
Zero
open-source license
Apache 2.0

Developed and supported by

National Cancer Institute Imaging Data Commons

The slide microscopy viewer of the NCI Imaging Data Commons

Slim is built and maintained by the Imaging Data Commons team, part of the National Cancer Institute's Cancer Research Data Commons. Every whole slide image in IDC, and the annotations, segmentations and maps computed from it, opens in Slim straight from the IDC Portal.

About IDCBrowse slides in the IDC Portal
of public cancer imaging data: radiology, pathology and fluorescence microscopy
>100 TB
to use, with no registration and no access requests
Free
of the data under CC BY, which allows commercial reuse
>95%
for every image and every annotation, segmentation and map
DICOM

The Imaging Data Commons has been funded in whole or in part with Federal funds from the National Cancer Institute, National Institutes of Health, under task order no. HHSN26110071 under contract no. HHSN261201500003l.

Features

Everything a pathology viewer needs, in DICOM

From the worklist to the last annotation, every object Slim shows or saves is a standard DICOM object on your archive.

Whole slide images, brightfield and fluorescence

Vendor-neutral display of DICOM VL Whole Slide Microscopy Image instances, from H&E brightfield to multiplexed immunofluorescence.

Annotations at the scale of single cells

Display ROI annotations from DICOM Comprehensive 3D SR and millions of cell outlines from Microscopy Bulk Simple Annotations.

AI and analysis results as overlays

Overlay segmentations, label maps and parametric maps from image analysis pipelines, with legends and per-segment controls.

Draw, measure and save as DICOM

Create region-of-interest annotations with coded findings and store them back to the archive as DICOM Comprehensive 3D SR.

A worklist that knows about derived data

Search studies, sort and page through results, and find the ones that hold segmentations, annotations, maps or presentation states.

A viewer layout built for slides

Collapsible side panels, viewport overlays and an overview map keep the slide in focus and the metadata one click away.

Any DICOMweb archive, any identity provider

Slim runs fully client-side in front of any DICOMweb-conformant PACS, VNA or cloud archive, with OpenID Connect sign-in.

Light, dark and yours

Dark by default, light on request, and preferences that apply immediately without reloading the slide.

Explore all features

Open data

Try it on real slides, one click away

Each example is public data in the NCI Imaging Data Commons (v24), served over DICOMweb by the IDC proxy and opened in the live demo.

See the full DICOM support matrix

Run your own

Deploy Slim next to your archive

Slim is a static web app. Point it at a DICOMweb server and serve the files from anywhere.

Runs Slim behind NGINX together with a dcm4chee-arc-light archive. The app is served at http://localhost:8008 and DICOMweb at /dcm4chee-arc/aets/DCM4CHEE/rs.

Shell
git clone https://github.com/ImagingDataCommons/slim.git
cd slim
docker-compose up -d

Then store slides in the archive with STOW-RS, for example:

Shell
pip install dicomweb-client
dicomweb_client --url http://localhost:8008/dcm4chee-arc/aets/DCM4CHEE/rs \
  store instances /path/to/slide/*.dcm

Release notes

What's new

Oct 1, 2026

Slim v2: the redesign

A new design system in light and dark, a modern toolchain, and a viewer rebuilt around hooks and tested pure functions. Existing viewer behavior is kept.

Read the release
  1. v0.46.10ci: build DMV when using git dependency from package.json
  2. v0.46.9ci: require open PR for matching DMV branch detection
  3. v0.46.8ci: escape hyphens in pnpm pkg set property path
  4. v0.46.7make worklist table body scrollable while keeping header/footer fixed
  5. All release notes

Showcase

Where Slim is used

From a national cancer imaging resource to DICOM interoperability testing and published research.

National Cancer Institute

NCI Imaging Data Commons

Slim is the slide microscopy viewer of the NCI Imaging Data Commons, a cloud-based environment of publicly available cancer imaging data.

slide microscopy series
76,000+
pathology segmentations
27,000+
bulk annotation series
7,000+
ProductionGoogle Cloud Healthcare APIPublic dataRead more

DICOM Working Group 26, Pathology

DICOM WG-26 connectathons

Slim demonstrated multi-vendor interoperability at the DICOM WG-26 Connectathon at Path Visions 2020 and the WG-26 Hackathon at Path Visions 2021.

WG-26 interoperability events
2
scanner vendors in the README test images
3
InteroperabilityMulti-vendorStandardsRead more

Nature Communications, 2023

Computational pathology research

The design and capabilities of Slim are described in a peer-reviewed article on interoperable slide microscopy viewing and annotation for imaging data science.

published in Nature Communications
2023
standard annotation output
TID 1500
Peer-reviewedAIAnnotationRead more

Open a slide in seconds

No install, no account. Open the demo on public IDC data, or read the docs to connect your own archive.

Open the demoRead the docs