This is about Splink, the UK government’s open-source record-linkage tool — not the payments app or the sales-incentive company that share the name.
The UK Ministry of Justice built a free tool, Splink, that stitches the separate records the state holds on you — justice, health, tax, benefits, census — into a single linked profile, even when those records share no common ID. It is lawful. It is spreading. And almost no one is told it is happening. This is a five-part investigation, built entirely from public documents and adversarially fact-checked.
Start here — the five parts
1. How Splink Works — the two-minute visual primer: no hack, no consent, no opt-out.
2. The Quiet Joining-Up — the original investigation, with the archived evidence locker.
3. Statistics or Operations? — the line the government drew, and where it stepped over.
4. Who Actually Uses Splink — fourteen adopters, tiered by what can be proven.
5. Ruled Unlawful Next Door — what the courts have, and haven’t, decided.
Frequently asked
What is Splink?
Splink is a free, open-source probabilistic record-linkage tool built by the UK Ministry of Justice. It matches records about the same person across separate datasets that share no common ID, using the Fellegi–Sunter statistical model.
Who uses Splink in the UK government?
Independently verified operational users are the Ministry of Justice and the Office for National Statistics (plus Australia’s Bureau of Statistics abroad). Splink’s own page also lists NHS England (whose live system is actually deterministic), the Department for Education, councils, Germany’s Destatis, the EU Medicines Agency and UNHCR — claims that are self-reported and, in several checked cases, unverified.
Is Splink used on my personal data?
If you have passed through the UK justice system, the NHS, or been counted in the 2021 Census, your records may have been linked using Splink or a similar tool. Linkage is generally lawful and done on de-identified data, but individuals are not told when their records are matched.
Can my records be linked without my consent?
In many cases, yes. UK law — including the Digital Economy Act 2017 and statutory powers under the Statistics and Registration Service Act 2007 — permits linking de-identified records for statistics and research without individual consent, notification or an opt-out.
Has Splink or MoJ Data First been ruled unlawful?
No. No court or regulator has ruled Splink, the Data First programme, the ONS Integrated Data Service or ADR UK unlawful. The activity operates within the existing legal framework — which is precisely what this investigation examines. The DPA 2018 immigration exemption next door, however, was ruled unlawful three times.
Is Splink just a statistics tool, or is it operational?
Both. It is mostly used for statistics and research. But the government’s own transparency records show the Ministry of Justice also uses it operationally — including a real-time court-linkage pilot and a daily feed of Police National Computer numbers from the North Essex Probation Delivery Unit to the police.
Built from public documents only; every claim sourced and adversarially fact-checked. Full evidence and the 14-profile master analysis: GitHub repository.