Calculator
What the Certificate Decoder does
Certificate Decoder: transforms Status and Certificate info from PEM certificate. Example: the sample loaded on the page gives status Not valid Base64.
Enter PEM certificate and the Certificate Decoder reports Status and Certificate info. Edit a field and the answer updates in place.
Typical users are developers debugging a payload. Spotting a malformed field is far quicker when the structure is laid out clearly.
Nothing leaves the tab. You can watch your browser network panel while you use it and see for yourself.
The meaning of each field, the formula in use, and a worked example that starts from the default inputs are all further down.
What do the Certificate Decoder fields mean?
The Certificate Decoder uses 1 input. You can work from the defaults, or clear them and start fresh, both work.
| Field | What to enter | Default |
|---|---|---|
| PEM certificate | paste or type any amount of text | -----BEGIN CERTIFICATE----- ... -----END CERTIFICATE----- |
How does the Certificate Decoder work?
Each output is derived from the inputs above in a single pass; there is no hidden state carried between runs, so the same inputs always give the same transformation.
Validation is deliberately strict: silently coercing a bad value is how wrong numbers get trusted.
Worked example
These are the values the Certificate Decoder loads by default, and the result it produces from them. Here is the calculation as it stands the moment the page loads.
| PEM certificate | -----BEGIN CERTIFICATE----- ... -----END CERTIFICATE----- |
|---|
| Status | Not valid Base64 |
|---|---|
| Certificate info | The text between the BEGIN and END lines is not valid Base64. Paste the full certificate, including every line of… |
How to use it
- Paste your content into PEM certificate.
- Because it recalculates as you type, you can dial a value in rather than guessing and re-running.
- You get Status and Certificate info back.
- Copy Link is the quickest way to send the exact scenario to someone else.
What this tool does not do
- Output follows the common convention for this format; a specific toolchain may have its own house style.
- Processing happens in your browser, so very large inputs are bounded by available memory.
- The output is a number, not a judgement. Deciding what it means is still your job.
Frequently asked questions
Only PEM certificate. Nothing starts empty, letting you treat it as a what-if tool rather than a data-entry form.
With the values loaded when the page opens, status comes out as Not valid Base64. Any edit re-runs the calculation, so there is no stale number on screen.
Nothing is stored. The page has no back end to send data to, and holds your input only in memory.
Nothing at all. There is no registration, no paywall and no per-use quota.
It matches what you would get working it out by hand, with fewer opportunities to slip.