Reverse Password Lookup: Where a Password Leaked
Searching a password runs the question backwards. Instead of asking what was leaked about an account, it asks which accounts a known credential unlocks. This is how you size the blast radius of a reused password across every service it was ever used on.
How a reverse password search works
Most lookups start with an identifier and ask what leaked alongside it. A password search runs the question backwards: you supply a credential and the result lists the accounts it appears with.
That is how you size the blast radius of a reused password. One search returns every service in the data where that exact value was captured, which is the list of places to change.
What a result contains
Every account using it
All records that contain this exact value.
Addresses and usernames
The identities attached to each occurrence.
Reuse scope
How many separate services the credential reaches.
Age
When each exposure occurred, which shows whether reuse is historical or current.
How to read the result
- This is the highest value search for anyone assessing their own exposure, because one result tells you how many places to change.
- Do not test a credential against a service you do not own. Knowing where it is exposed is the finding, not the access.
Modules queried
- Snusbase
- LeakCheck
- Community breach dumps
- Combo lists
Each row in a result set names the module it came from, so findings stay traceable.
Questions
Is it safe to type my password into a lookup?
The value is sent over TLS, used for the search, and not saved to your account history. If you would rather not type a live password, search one you have already changed.
Why does the result include accounts I do not recognise?
A reused credential appears in every service that leaked it, including accounts created years ago and forgotten. That is the point of the search: it is the list of places to change.
Does a match mean someone is in my account?
It means the credential was captured in a breach. Whether it was used depends on the service and the age of the leak. Treat every match as a password to change rather than a sign of access.
What does one lookup cost?
The first lookup on a new account is free and reveals one record in full. After that, a lookup costs $1.75 in credits, or comes out of a plan allowance: $19.99 for 15 a day, $39.99 for 50 a day. A search that returns nothing costs nothing.