> For the complete documentation index, see [llms.txt](https://notes.programmersecurity.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://notes.programmersecurity.com/ctfs/regex-bypass.md).
# Regex Bypass
## Regex101
If we want to bypass a regex, first we need to understand it. for that i will be going to use the below link
{% embed url="" %}
lets say we have the following regex
```python
^([a-zA-Z0-9_.-])+@(([a-zA-Z0-9-])+.)+([a-zA-Z0-9]{2,4})+$
```
i will paste this to **regex101** and try to understand it
now i will try to add a random email address to see wether i can bypass the regex or not, and i can see that my email has been caught by the regex
now i will try to bypass it using the following email
```python
jjjjjjjjjjjjjjjjjjjjjjjjjjjj@ccccccccccccccccccccccccccccc.55555555555555555555555555555555555555555555555555555555.
```
and now regex has been bypassed
## JEX.IM
We can use the Second website to understand the regex
{% embed url="" %}
so i can paste the same regex used above and understand it