CRD File Documentation

Summary

A CRD file most often means one of two unrelated things. On modern Windows it is a Windows CardSpace information card: an XML file that stored the metadata of a digital identity (a “managed” or “self-issued” InfoCard) for the discontinued CardSpace identity selector. The older and still very common meaning is a Windows Cardfile database, a binary index-card file from the Cardfile applet that shipped with Windows 1.0 through 3.x. Check the file’s contents to tell them apart: a Cardfile starts with MGC, a CardSpace card is readable XML.

Technical details

FeatureValue
Extension.crd
Meaning 1Windows CardSpace information card (InfoCard)
Meaning 2Windows Cardfile database (index-card PIM)
DeveloperMicrosoft (both meanings)
CardSpace format typeXML metadata describing one digital identity card
CardSpace introduced.NET Framework 3.0 / Windows Vista (2006)
CardSpace statusDiscontinued — CardSpace 2.0 cancelled 15 Feb 2011
CardSpace contentsCard name, card image, and STS (security token service) details
Cardfile format typeLegacy binary card database
Cardfile shippedWindows 1.0 (1985) through 3.x; dropped as a default app after Windows 95
Cardfile magicMGC (Windows 3.x) or RRG (later variant) at offset 0
Open standardNo (both are proprietary Microsoft formats)
Other usesGuitar/ukulele chord charts; OrCAD Capture schematic data
CardSpace successorNone shipped (Microsoft moved to U-Prove, then other identity tech)
Related extensions.vcf, .csv, .txt, .xml, .mdb
Telling the two .crd formats apart

Open the file in a text editor. A Windows CardSpace information card is XML text — you will see tag markup describing the card name, image and token-service (STS) details, and it may be encrypted if it was a roamable exported card. A Windows Cardfile database is binary and begins with the 3-byte marker MGC (4D 47 43, the classic Windows 3.x format) or RRG for the later double-byte variant, followed by the card records. If the first bytes are readable angle-bracket XML, it is CardSpace; if they are MGC/RRG and the rest is unreadable, it is Cardfile.

What is a CRD file?

The .crd extension is used by two entirely separate Microsoft formats, and which one you have changes everything about how to open it. The format this page is named for is Windows CardSpace: a .crd here is an information card, an XML file that stored the metadata of a digital identity for the CardSpace identity-selector technology that shipped in .NET Framework 3.0 and Windows Vista in 2006. The other, older and in practice more frequently encountered meaning is a Windows Cardfile database, a binary file of index cards created by the Cardfile applet bundled with Windows from version 1.0 (1985) through 3.x.

These formats have nothing in common beyond three letters. A CardSpace card is readable XML describing an identity; a Cardfile database is a binary stack of address/note cards. Because both are real, the practical first task is to work out which one you are looking at, then use the matching tool. This article covers CardSpace first (the format the page is named for), then Cardfile, and ends with how to distinguish and migrate them. A handful of unrelated programs — some guitar-chord apps, and Cadence OrCAD Capture — also emit files called .crd, but those are niche.

Windows CardSpace: the information card and what it holds

Windows CardSpace (codenamed InfoCard) was Microsoft’s client for the Identity Metasystem, an architecture meant to let people carry a set of digital identities across sites the way physical cards sit in a wallet. In the CardSpace UI each identity appeared as a visual card. When a card was created or provisioned it was stored as a .crd file, and that file is metadata, not credentials: it records the card’s display name, its card image, and the details of the security token service (STS) that issues tokens for it. When a website asked for identity, CardSpace used those details to contact the issuer and obtain a digitally signed XML token containing the requested claims; the token, not the .crd, is what proved anything.

There are two card kinds. A self-issued (personal) card holds a small set of claims the user asserts about themselves, backed by a self-issued token service on the local machine. A managed card points at an external identity provider’s STS, so the actual claims come from that provider. Roamable cards could be exported so they moved between machines, in which case the exported .crd is encrypted under a password. CardSpace was discontinued: on 15 February 2011 Microsoft announced that CardSpace 2.0 would not ship, and the technology was retired, so a .crd CardSpace file today is a leftover from that era rather than something in active use.

Windows Cardfile: the MGC index-card database

The older meaning of .crd is a Windows Cardfile database. Cardfile was a tiny personal-information manager bundled with Windows from 1.0 through 3.x: an on-screen stack of index cards, each with a single indexed title line and a free-text body, used for addresses, phone numbers and notes. Microsoft stopped installing it by default after Windows 95, so a Cardfile .crd is almost always a decades-old file someone is trying to recover.

The format is a simple binary index. A genuine Cardfile begins with the 3-byte marker MGC for the classic Windows 3.x format, or RRG for the later double-byte variant, followed by a card count, the sorted index (title) lines, and then the card bodies. Early versions could embed an OLE object or bitmap in a card body, but most files are plain text cards. Because the applet is gone from modern Windows, opening a Cardfile .crd takes one of three routes: run the original CARDFILE.EXE copied from an old system (the 32-bit Windows 95/NT build still launches on Windows 10 and 11; the 16-bit build needs a DOS/Windows 3.x emulator on 64-bit Windows), use the maintained third-party AZZ Cardfile, which imports classic .crd files, or extract the text with a free CRD reader tool and move the contacts into a modern format.

Telling CardSpace and Cardfile apart, and getting the data out

The two formats are trivial to distinguish by their first bytes. Open the .crd in a text editor: if you see angle-bracket XML (or an obviously encrypted blob that a CardSpace export produced), it is a CardSpace information card; if you see the binary marker MGC or RRG followed by unreadable bytes, it is a Cardfile database. That single check tells you which toolset applies.

Getting the data out depends on which one it is. A CardSpace .crd holds only card metadata pointing at an identity provider that no longer runs, so there is generally nothing useful to recover from it and no reason to import it into anything current; the safe action is usually to leave it or delete it. A Cardfile .crd, by contrast, often holds contacts worth migrating. The practical path is to open it in a Cardfile reader and export the card text to CSV, then import that CSV into Outlook or Google Contacts, and if you want a phone-ready contact file, save it as vCard (VCF). For a plain archival copy, the free CRD reader dumps the card text to TXT, or you can print from CARDFILE.EXE to PDF. Avoid generic “CRD viewer” download sites, which tend to bundle adware and often cannot open either real format.

Frequently asked questions

Is my .crd a CardSpace card or a Cardfile database?

Open it in a text editor. Readable XML markup means a Windows CardSpace information card. Binary content beginning with MGC or RRG means a Windows Cardfile database. They are unrelated formats that happen to share the extension, so the check decides which program you need.

Can I still use a CardSpace .crd file?

Not in any practical sense. Windows CardSpace was discontinued after Microsoft cancelled CardSpace 2.0 in February 2011, and the identity providers a managed card pointed to are long gone. The .crd stores only card metadata (name, image, token-service details), not usable credentials, so there is nothing to log in with today.

How do I open an old Cardfile .crd on Windows 10 or 11?

Run the original CARDFILE.EXE (the 32-bit Windows 95/NT build still launches on Windows 10 and 11) and use File › Open, install the third-party AZZ Cardfile to import it, or extract the text with a free CRD reader tool. To keep the contacts, export them to CSV and import that into your current address book.

References