# Free fail2ban tools

> Free fail2ban tools in your browser: an online fail2ban-regex tester, filter and jail.local generators, bantime calculator, log analyzer and command builder.
>
> Source: https://fail2ban.dev/tools/ · Updated 2026-10-25 · Checked against fail2ban 1.1.1
> fail2ban.dev is an independent guide, not the official fail2ban project.

- [fail2ban regex tester](/tools/regex-tester/) — paste log lines, choose any of the 96 built-in filters or your own failregex, and see what matches and which IPs would be banned
- [Filter generator](/tools/filter-generator/) — click the IP in one log line and get a complete filter.d file, a jail and the test command
- [jail.local generator](/tools/jail-generator/) — pick distro, firewall and services; copy a clean, commented jail.local
- [Log analyzer](/tools/log-analyzer/) — find attacking IPs, failures per hour and usernames tried in auth.log or web logs
- [Bantime calculator](/tools/bantime-calculator/) — convert 1d12h, 1w or 1mo to seconds and simulate incremental bans
- [Command builder](/tools/command-builder/) — the exact fail2ban-client command to unban, ban, whitelist or check status

## Which tool do I need?

| You want to… | Use |
|---|---|
| Check whether a filter catches your log lines | [Regex tester](/tools/regex-tester/) |
| Protect an app fail2ban has no filter for | [Filter generator](/tools/filter-generator/), then the [regex tester](/tools/regex-tester/) |
| Set up fail2ban on a new server | [jail.local generator](/tools/jail-generator/) |
| See who is attacking you and what fail2ban would ban | [Log analyzer](/tools/log-analyzer/) |
| Pick `bantime`, `findtime` and incremental settings | [Bantime calculator](/tools/bantime-calculator/) |
| Unban someone right now | [Command builder](/tools/command-builder/) or [unban an IP](/unban-ip/) |

## How the tools work

The regex tester, filter generator and log analyzer share one engine: a JavaScript port of the parts of fail2ban that decide whether a line is a failure — date detection with fail2ban's own date templates, `prefregex`, `failregex`, `ignoreregex`, the `<HOST>` and `<F-…>` tags and multi-line failure IDs. The built-in filters are extracted from fail2ban 1.1.1 and translated from the exact regexes fail2ban compiles. We check the engine against fail2ban's own results on the 1,028 sample log lines in fail2ban's test suite; it agrees on 99.7% of them.

The tools are a fast way to iterate. Before you rely on a filter in production, confirm it on the server with [`fail2ban-regex`](/fail2ban-regex/).

## FAQ

### Is it safe to paste server logs into these tools?

Yes. The pages download the filter definitions once and do all processing in your browser; no log content is sent to any server. You can even disconnect from the network after the page loads.