How verification works

How verification works

A candidate passport brings together account checks, verified work activity and code assessments. Published results use W3C Verifiable Credentials, so readers can check who issued a result, whether it has changed, and whether it is still valid.

• Account connection. The candidate signs in with GitHub at our app. This links the passport to an account they control.
• Organisation and work checks. For supported checks, the candidate uses the 16 Signals browser extension in their own signed-in GitHub session. The result describes the claim we checked, such as membership or work activity. A membership result alone is not evidence of technical ability.
• Code assessment. We analyse projects the candidate selects and report findings supported by the available code. This is an assessment of the submitted evidence, not a complete record of everything the candidate has built.

Linked, Proven and Assessed

Each card on a passport carries one of three labels.

• Linked means the account was connected through sign-in. It shows that the candidate controls the account. It is not a claim about the work done with it.
• Proven (zkTLS) means 16 Signals checked a supported claim against evidence from the candidate's GitHub session. The credential states what was checked and what a third party can verify. The label does not mean every underlying claim can be independently reconstructed.
• Assessed means 16 Signals analysed repositories the candidate selected and signed the result. It is our assessment, not a cryptographic proof, and it is labelled as such.

Verifiability levels

Every credential also states how far a third party can check its claim without trusting us. There are two levels.

• Attested: you can verify that 16 Signals issued the result, but the published evidence is not enough to reconstruct the underlying claim. You rely on our verification or assessment.
• Re-derivable: some organisation-membership credentials include supporting evidence that lets readers re-check the stated membership. This does not independently verify the original private session. See what independent verification covers.

Who can unlock a passport, and who pays

A published passport page is public. Employers who use 16 Signals can also search published passports by verified stack and by method, and unlock a candidate's full report. The candidate does not choose which employer unlocks: any of these employers can unlock a published passport. Candidates are never charged.

• Unlocking is free for an employer that already has a finished report for that candidate from one of its own jobs.
• Each employer starts with one free unlock.
• Otherwise an unlock costs the employer 1 Deep Scan credit. Unlocking the same candidate again costs nothing.
• The report can be opened only while the passport is published. If the candidate unpublishes, the employer loses access to it, and the credit is not refunded.
• After unlocking, an employer can add the candidate to a job. Screening the candidate's public GitHub for that job costs the employer 1 screening credit at once. Inviting the candidate is free to send, and the employer is charged 1 Deep Scan credit when the candidate submits.

The full report adds paid details to the public cards: for a membership, the organisation's legitimacy and the candidate's role and activity in it; for verified work in a private organisation, findings about that work; for code, evidence from the analysed repositories. It never includes a hidden organisation's name or a hidden card, and employers never receive the candidate's e-mail address.

What the candidate controls

• Hide an organisation's name. The membership card then describes the organisation only by its tier, for example “an established private organisation”. The name is also left out of the credentials and of the employer report, together with that organisation's languages. Verified private work never names the organisation, hidden or not.
• Hide a whole card. A hidden card disappears from the page, the credentials, the snapshot, employer search and the employer report. The GitHub account card cannot be hidden.
• Search-engine indexing. Off by default: the page asks search engines not to index it. The candidate can turn on a setting that lets search engines index the page, and turn it off again at any time.
• Unpublish. The page goes offline and its credentials are revoked. The evidence is kept, so the candidate can republish without proving everything again.
• Erase. Deleting the account revokes the credentials and deletes the passport and its evidence.

W3C credentials and how to check them

Published passport results use the W3C Verifiable Credentials 2.0 standard. Each credential is digitally signed by 16 Signals and identifies its issuer, the claim, its validity period and its current status. The passport lists current credentials.

1. Check the issuer and signature. Verification checks that the credential was issued by 16 Signals and has not been altered, using our published verification keys.
2. Check its status. A credential may have been revoked or replaced. A saved copy or screenshot is not enough to establish that it is still current.
3. Check the dates and scope. Read the validity period, what the credential says was checked, and any limitations attached to that result.

A valid signature establishes the source and integrity of a result. It does not turn an assessment into a fact, establish technical ability, or guarantee a hiring outcome.

What independent verification covers

Every credential can be checked for its issuer, signature, status and validity period. Some membership credentials also include supporting evidence for re-checking the membership claim. The credential shows whether this is available; it should not be assumed for every result.

Where an organisation is hidden or supporting evidence is unavailable, the claim remains an attestation by 16 Signals. Readers cannot reconstruct it from the published credential alone.

What you are trusting

16 Signals is the issuer and is responsible for the checks and assessments it signs. Readers can verify a credential's integrity without treating every conclusion in it as independently proven.

Private-session checks rely on 16 Signals having witnessed and reported the evidence accurately. A third party cannot repeat the original private-session verification from the credential. Additional published evidence can help check a specific claim, but does not remove that reliance on the issuer.

Limits

• Coverage depends on available evidence. A code assessment covers selected repositories and contributions we can attribute to the candidate. Missing evidence is not proof of missing ability, and the result does not establish sole authorship or ownership of a production system.
• Not every membership can be re-checked independently. Availability depends on the supported check, candidate eligibility and what they choose to publish. The credential states its verification level. Hidden organisations and cards are not offered as re-derivable results.
• Credentials expire and are re-issued. A credential is valid for a limited period. New evidence replaces it with an updated one, and the old one is marked as replaced. An expired or replaced credential drops out of the passport.
• Assessments are decision support. Use the findings to decide what to explore next. They supplement your interviews and assessments; the hiring decision stays with you.

How long evidence is kept

• Evidence expires 12 months after it was collected and is deleted 30 days after it expires.
• The paid details an employer sees after an unlock are copied into the candidate's own evidence when it is collected. The candidate owns this copy, so the report stays complete even if the employer whose job produced a proof or analysis later deletes their account. The copy is deleted with the evidence, or when the candidate deletes their account.
• Unpublishing keeps the evidence; deleting the account removes it.

What is never public

• The names of repositories that were analysed. Only a count and the stacks that passed are shown.
• The full report. It is shown only to an employer that unlocked the passport, as described above.
• Full pages captured during a private-session check. Some membership credentials include limited supporting evidence. Those public supporting details are deleted within an hour when the candidate unpublishes or hides that organisation or card.
• Anything job-specific, such as how a candidate was scored for a role.

See the Privacy Policy for how personal data is handled.