CSR Decoder

Decode Certificate Signing Requests in PEM format.

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Input
Output
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About csr decoder

CSR Decoder is a small tool that does one job while you watch. Nothing is saved, so a reload gives you a clean start.

Once the page has loaded it needs nothing further from the network. Work on a plane, on a train, or behind a firewall that blocks everything.

You will find it under Keys & certificates, alongside 7 other tools for the same sort of job.

Displays subject fields, algorithms, and OIDs from PKCS#10 CSR data.

How to use it

01
Start it
Every control is on the tool itself. Keyboard shortcuts, where there are any, are listed beside it.
02
Watch it run
It updates in the page as you go. Nothing is sent anywhere, so it keeps working with the network off.
03
Close when done
Nothing is stored between visits. Reloading gives you a clean start rather than picking up where you left off.

Examples

Decode CSR
Decode a PEM-encoded Certificate Signing Request
Input
-----BEGIN CERTIFICATE REQUEST-----
MIICoDCCAYgCAQAwWzELMAkGA1UEBhMCR0IxDzANBgNVBAgMBkxvbmRvbjEPMA0G
A1UEBwwGTG9uZG9uMRQwEgYDVQQKDAt1dGlscyB0b29sczEUMBIGA1UEAwwLZXhh
bXBsZS5jb20wggEiMA0GCSqGSIb3DQEBAQUAA4IBDwAwggEKAoIBAQDNtzHi1+Pw
r6VfMZ7uKGlQ7wBlIq1MhY5AgR4JhCOejG/QYYGv0ZT2+Itle9R0OLjB5mSjJcEk
Zt0uxbY62mi1ywxSTYxHPETrUEHdBQkGUgryHhKOYcauvBAVujjx8qcOvsj+yTXt
NGaKX3h3qECwaHLKgk6qVCniAnm1Fml3DDNg28w6buONiRPJNDar4nLDUMN6bCLQ
ZGu24HdyIPQ6CX8HyVTy56Qry+raIOItcfolYv33uUs0kkGv+gfs1uFuk0NHYNnt
UDiVTI80MGxef325UXDS56jtKuU57Vm7PtdDLXF2ishIt+nhkVSTkhp/QnKTKwkt
QDi7SUn5JQVXAgMBAAGgADANBgkqhkiG9w0BAQsFAAOCAQEAzCE9rbB4Fa3wvjPG
lwVExilRsDhFf8Dg4yvmCjpJ1Xdce1nr3L/72hng07/CkWB2e/6bSjMegLX7zwM1
fQEdbw0pPxCoOgRYsc716CSBdy6ZAoaxWnnyWom09OAj82CYYpyjc5SJACWVIWlf
eNct4ZwvG6jJizLFZHNp9Me1PAxNRcm8oRdyGjxRO07cNRNdu/ATGGLok4/Gtprc
As9kap7vaZFCBX+8azi5NpvVXsBmUL9h7hqo+CCW3nmEig3U0NDIELIuQ5foFf4L
ZonmkFGXF/vRy27gdmaPGCbpclDHs6QrbAEf1cVLnzTTulf/O0wLLUb0c3cG2y1r
LjWuGg==
-----END CERTIFICATE REQUEST-----
Output
=== Certificate Signing Request ===
Total size: 676 bytes

Subject:
  Country (C): GB
  State (ST): London
  Locality (L): London
  Organization (O): utils tools
  Common Name (CN): example.com

Algorithms/OIDs found:
  Country (C) (2.5.4.6)
  State (ST) (2.5.4.8)
  Locality (L) (2.5.4.7)
  Organization (O) (2.5.4.10)
  Common Name (CN) (2.5.4.3)
  RSA (1.2.840.113549.1.1.1)

Questions

Does CSR Decoder work offline?+

Yes. It is JavaScript running in this tab, so once the page has loaded it needs nothing further from the network. Put the machine in flight mode and it carries on. Nothing you do here is sent anywhere, because there is nowhere for it to go.

Does it remember anything between visits?+

No. Reload the page and it starts from nothing. There is no account, no saved state and no cookie holding your last session. That is a deliberate trade: it cannot lose your data because it never keeps any.

Is it accurate?+

Timing comes from performance.now(), the high resolution clock the browser provides, rather than from setInterval, which drifts by a few milliseconds every tick and compounds over minutes. What can still shift things is the browser throttling a tab in the background, so leave it visible if the timing matters.

Does it make a sound?+

Where a sound makes sense, it is generated with the Web Audio API rather than loaded as a file, so there is nothing to download and nothing to block. Browsers refuse to start audio until you have interacted with the page, which is why the first press is what switches it on.

Can I use CSR Decoder on a phone?+

Yes. The controls are sized for touch and the layout collapses to one column on a narrow screen. Bear in mind that a phone locking its screen will suspend the page, and timing stops with it.