Univik RSMF File Viewer
Key Facts
The Short Version
Who Needs It
Opposing Counsel Productions
A law firm receives chat evidence produced as .rsmf files in litigation discovery. The firm reviews the conversations without buying a Relativity seat for one matter.
Univik RSMF File Viewer
Open RSMF Files without Relativity
Univik RSMF Viewer is a free Windows tool that opens Relativity Short Message Format (.rsmf) files and shows every conversation as readable chat bubbles. Review text messages, Slack threads, Teams chats and WhatsApp exports from an eDiscovery production without a Relativity licence.
100% FreeWorks OfflineNo Sign-upNo Watermark
- No Relativity Needed: Read any .rsmf file on a plain Windows PC.
- Real Chat View: Conversations render as chat bubbles with sender, time and direction.
- RSMF 1.0 and 2.0: Both published versions of the format are supported.
- Attachments Included: Preview images and save any attached file out of the archive.
- 100% Offline: Evidence never leaves your machine, which keeps review GDPR-compliant.
Key Facts
Univik RSMF Viewer at a Glance
Six answers about the RSMF format before you even scroll.
$0
Completely Free
Univik RSMF Viewer opens Relativity Short Message Format files free of charge, with no registration and no watermark.
2
Format Versions
It reads both published versions of the format, RSMF 1.0 and RSMF 2.0, including read receipts and message direction from 2.0.
75+
Source Platforms
RSMF files carry chats from more than 75 platforms, including SMS, iMessage, Slack, Teams, Skype, Bloomberg and WhatsApp.
RFC 5322
Open Structure
An RSMF file is an RFC 5322 email wrapper holding an rsmf.zip archive with a manifest named rsmf_manifest.json.
100%
Offline and GDPR-Compliant
Every file is parsed locally on your own Windows PC. Nothing leaves the machine, which matters when the file is legal evidence.
0
Relativity Licences Required
The viewer needs no Relativity environment, account or licence to open and read an .rsmf file.
The Short Version
Why You Need a Viewer
An RSMF file is Relativity Short Message Format, the standard container for chat evidence in eDiscovery. When texts, Slack channels, Teams chats or WhatsApp threads are collected for a legal matter, they are packaged into .rsmf files so review platforms can show them like documents.
"The RSMF is essentially a .zip, which is wrapped in a traditional .eml file."
- Relativity documentation
The catch: that packaged data is not readable outside Relativity's own viewer, which normally means a paid Relativity or RelativityOne licence. Univik RSMF Viewer opens the file directly on Windows instead. If you want the full technical breakdown of how the format is built, see our reference guide on what an RSMF file is and how it works.
Who Needs It
When an RSMF File Lands on Your Desk
RSMF files show up across legal and forensic work. If any of these is you, the viewer was built for exactly this moment.
Forensic Examiners
Mobile forensic suites such as Cellebrite can export per-custodian chat extractions to RSMF. Examiners verify the export reads correctly before handing it to the legal team.
Compliance and HR Teams
Internal investigations produce RSMF packages of Teams or Slack history. Investigators read the threads locally without routing evidence through a cloud tool.
eDiscovery Vendors
Processing teams spot-check RSMF files they generate for clients. A quick local open confirms participants, threading and attachments before delivery.
Three Steps
Three Steps
How to Open an RSMF File in 3 Steps
Install, open, read. No Relativity account, no import job, no waiting on a processing queue.
1
Install the Free Viewer
Download and run the installer on any Windows 11 or Windows 10 PC. No account is needed.
2
Open the .rsmf File
Drag the file into the window or use File, then Open. The viewer unpacks the wrapper and manifest on the spot.
3
Read the Conversations
Pick a conversation, scroll the bubbles, search for names or keywords and save out any attachment you need.
Download the Free Viewer
Windows 11, 10 and Server · no Relativity account · nothing uploaded
What You Need
System Requirements
The viewer is a light desktop app. If you can run a browser, you can run this.
Operating System
Windows 11 and Windows 10, both 64-bit. Older Windows Server builds also run the viewer for teams working on a review server.
Memory and Disk
4 GB RAM is enough for everyday files. Large productions with thousands of messages and attachments read faster with 8 GB. The install itself is small.
No Extra Software
No Relativity account, no database engine and no Microsoft Office install are needed. The viewer reads the .rsmf file on its own.
No Internet Required
The viewer works fully offline. An internet connection is used only to download the installer, never to open or process a file.
When to Use Which
When to Use Which
Univik Viewer vs the Relativity Viewer
Both read RSMF. They are built for different jobs. Here is the honest split.
Use the Univik viewer to read a file quickly. Use Relativity when you are running the full matter inside a workspace.
Versions
RSMF 1.0 vs RSMF 2.0
Two versions of the format exist. Univik RSMF Viewer reads both, so you never need to ask which one you were sent.
FAQ
FAQ
RSMF Viewer Questions
Yes. Univik RSMF Viewer reads the .rsmf file directly on Windows. It parses the RFC 5322 wrapper, the rsmf.zip archive and the rsmf_manifest.json manifest itself, so no Relativity environment, account or licence is involved.
Yes. Univik RSMF Viewer is free for personal and commercial use. There is no watermark, no registration and no time limit.
The viewer shows the conversation as chat bubbles in time order, a list of every participant and each message with its timestamp. Images preview inline and any attachment can be saved out with one click. For a full breakdown of how an RSMF file is built, see our RSMF file format guide.
Yes. Any tool that writes standard RSMF 1.0 or 2.0 files produces output the viewer can read, including chat extractions exported from mobile forensic suites such as Cellebrite.
No. All parsing happens on your own Windows PC and the viewer opens files read-only. Nothing is uploaded, which keeps the review GDPR-compliant and the chain of custody clean.
RSMF normalises chat data from more than 75 platforms. Common sources include SMS, Apple iMessage, Slack, Microsoft Teams, Skype, Bloomberg chat and WhatsApp. The viewer shows whatever the file contains, whichever platform it came from.
The viewer is for reading and saving attachments out of the file. Since an RSMF file is built on a standard email wrapper, Univik EML Converter handles the container level if you need file conversion around your workflow.
Univik RSMF Viewer runs on Windows 11 and Windows 10, both 64-bit, and on Windows Server. 4 GB of RAM handles everyday files and 8 GB helps with large productions. No Relativity account, database engine or Office install is needed, and the viewer works fully offline.
The Relativity viewer is part of a full review platform for running a whole matter, with search, coding and production, and it needs a licensed seat. Univik RSMF Viewer is a free desktop tool for reading a single .rsmf file quickly on any Windows PC. Use Univik to read a file, use Relativity to work the case.
Still have questions? Contact support or Live Chat
Related Tools
More Univik Tools for Message Evidence
EML Converter
Convert EML email files, the same wrapper standard RSMF is built on, to PST, PDF and 13 more targets.
EML Converter »MSG Converter
Batch convert Outlook MSG message files to PST, EML, PDF and more for review workflows.
MSG Converter »PST Converter
Open and convert Outlook PST mailboxes without Outlook installed, including deleted item recovery.
PST Converter »Univik Research Team
Data & forensic software
Since 2013
About This Page
The Univik Research Team has been building data conversion and forensic software since 2013. Our engineers work with email container formats every day, including RFC 5322, EML, MSG and PST, the same family the RSMF format is built on. Content on this page is checked against Relativity's published RSMF documentation.
Related tools: EML Converter | MSG Converter | PST Converter