Cap’n Proto is an insanely fast data interchange format and capability-based RPC system.
Publisher’s description
What is Cap’n Proto?
Cap’n Proto by Cap’n Proto is open-source Windows software.
Installation and requirements
The publisher provides Portable installers for 32-bit Windows. The main installer is 4.6 MB. It runs without installation (portable).
Updates and version history
The current version is 1.1.0, released on March 8, 2025. The version history goes back to May 25, 2023: 2 releases, all linked to the official files. That is about 1.1 releases a year. The last update is more than a year old.
Pros / Cons
Pros
- Open source: the code can be inspected and built by anyone
- Portable: runs without installation
- Small download (4.6 MB)
Cons
- No native ARM64 build
- 32-bit only
- No update for more than a year
In short: Cap’n Proto is an open-source Windows tool for 32-bit PCs. Updates have slowed down.
Is Cap’n Proto safe to download?
- The file is served by capnproto.org; check that it is the publisher’s official mirror
- The download link uses HTTPS
- A SHA256 hash is published, so you can verify the file:
623B7525501D410E6479C8029EBA265AA57AC8153C6FA09AB21A62F906B3E3F9· Open the VirusTotal report for this hash - The link answered when we last checked it (October 22, 2026)
- The source code is public
- ExeAtlas does not host, wrap or modify installers
Related guide: How to check a file’s SHA256 hash on Windows
Recent versions
All 2 versions ›2 versions over 2 years · about 1.1 a year
| Version | Date | Size | Files |
|---|---|---|---|
| 1.1.0Latest | March 8, 2025 | 4.6 MB | 32-bit ZIP |
| 0.10.4 | May 25, 2023 | — | 64-bit ZIP |
Install from the command line
Silent install ›winget install --id capnproto.capnproto -eRelated guide: How to use winget: install and update apps
Information
- Publisher
- Cap’n Proto
- Licence
- MIT License
- Price
- Free
- Requires
- Windows 11 / 10
- Architecture
- 32-bit
- Installer
- Portable
- Version
- 1.1.0
- Released
- March 8, 2025
- Added to the catalogue
- May 25, 2023
- Versions listed
- 2
- Updates / year
- 1.1
- winget ID
- capnproto.capnproto
Ratings and reviews
No reviews yet. Be the first to rate it.
Frequently asked questions
Is Cap’n Proto free?
Yes. Cap’n Proto is open-source software under the MIT License licence.
Is Cap’n Proto safe to download?
The download comes from capnproto.org; ExeAtlas does not host or change the file. Compare its SHA256 hash with the one shown here, or open the VirusTotal report for that hash.
How do I install Cap’n Proto with winget?
Open PowerShell or Windows Terminal and run the winget command shown on this page. winget downloads the official installer and checks its SHA256 hash before running it.
Does Cap’n Proto run on ARM (Windows on Arm)?
There is no ARM64 build; Windows 11 on Arm can run the 32-bit version through emulation.
Where can I download an older version of Cap’n Proto?
The versions page lists all 2 versions with links to their official installer files, back to May 25, 2023.
Can I use Cap’n Proto without administrator rights?
Yes, it is portable: unpack and run it.