Wordlist Filtering¶

Wordlist filtering lets you derive a smaller, targeted wordlist from a larger one by keeping only the words that match criteria you choose — for example, "only words 8–16 characters long that contain an uppercase letter, a digit, and a symbol." This trims candidates that can't possibly satisfy a known password policy, so jobs finish faster without wasting work.

You can filter in two ways:

For a single job (on the fly): apply a filter while creating a custom job. KrakenHashes builds a temporary, job-scoped wordlist that exists only for that job.
As a reusable wordlist: create a permanent filtered wordlist on the Wordlists page that you can select in any future job, just like any other wordlist.

Filter criteria¶

The same criteria are available in both places. A word is kept only if it satisfies every criterion you set (the criteria are combined with AND). Leave a field blank to ignore it.

Criterion	Meaning
Min length / Max length	Bounds on word length, measured in characters (not bytes — multi-byte characters count as one).
Required character classes	Require any of: Uppercase, Lowercase, Digit, Special (a printable ASCII symbol — non-alphanumeric). Each box you check must be present in the word.
Min # of classes (1–4)	Require at least N of the four classes to be present — e.g. `3` keeps words that mix at least three of upper/lower/digit/special.
Regex (RE2)	A regular expression the word must match. Uses the Go RE2 engine, which runs in linear time (no catastrophic backtracking).

Regex engine: RE2, no lookarounds

The regex field uses RE2, which does not support lookaround assertions ((?=…), (?!…), (?<=…), (?<!…)). The form flags these as you type. Most "require a class" rules are better expressed with the length and character-class fields above than with a regex. A simple length pattern like ^.{10,16}$ is fine.

If two criteria overlap, the stricter one wins — e.g. setting min length 8 but a regex that requires 12+ characters effectively requires 12+.

Live preview¶

When a source wordlist is selected, the form shows a live estimate such as ~1,200,000 candidates (24.3% of sample). This is produced by sampling the start of the source wordlist (the first ~1,000,000 lines) and extrapolating, so it is fast even for huge files.

Estimates are sampled

Because the preview samples the beginning of the file, the true total can differ for wordlists that are sorted or front-loaded (for example, a list ordered shortest-to-longest will skew a length filter's estimate). Treat the number as a guide, not an exact count.

Filtering a wordlist for a single job¶

When you create a custom job, enable the wordlist filter option, choose your source wordlist(s), and set the criteria. On submit:

The job is created in a preparing state while KrakenHashes generates the temporary (job-scoped) filtered wordlist in the background and then measures its keyspace.
Once both finish, the job automatically moves to pending and the scheduler picks it up — no further action needed.
If generation fails (for example, the filter matches zero words), the job is marked failed with the reason, and the temporary wordlist is cleaned up.

Every custom job now starts in preparing

This is no longer specific to filtered jobs — all custom jobs are measured in the background, so they all pass briefly through preparing. See What "Preparing" means.

These job-scoped filtered wordlists are temporary: they belong to the job that created them and are not added to your general wordlist library.

Creating a reusable (permanent) filtered wordlist¶

If you'll reuse a filter, create a permanent filtered wordlist instead:

Go to the Wordlists page and click Filtered Wordlist.
Pick a Source wordlist. Only verified, non-potfile, non-filtered wordlists can be used as a source.
Give it a Name (a default like MyList (filtered) is suggested).
Set your filter criteria and check the live preview.
Click Create.

The wordlist is generated in the background. It appears in the wordlist table immediately with a Filtered badge and a status that progresses through:

Status	Meaning
Pending	Generation in progress (first build).
Verified	Ready to use — selectable in jobs and downloadable.
Failed	Generation failed (e.g. the filter matched no words).
Regenerating…	The parent changed and the filtered list is being rebuilt.
Stale	The parent changed since this was generated; a refresh is queued or can be triggered manually.

Once Verified, a filtered wordlist behaves exactly like any other wordlist — select it when creating jobs, download it, edit its metadata, or delete it.

Keeping filtered wordlists up to date¶

A filtered wordlist remembers the parent it was derived from.

Automatic regeneration: When the parent wordlist changes, KrakenHashes regenerates the filtered copy automatically. When the parent was only appended to (new words added to the end), it does this incrementally — only the new lines are filtered and appended — which is fast even for large lists.
Manual full regeneration: The Regenerate (↻) action forces a complete rebuild from the parent. You normally don't need this; use it only if the parent's existing words were edited, removed, or reordered (not just appended), since the incremental path assumes append-only changes. A full regeneration re-filters the entire parent and can take a while for large lists.