# Zero Drift > Zero Drift Ltd is a UK software studio that builds complete, deterministic, cheap-to-run software for regulated markets. This is zerodrift.co.uk, not the US company ZeroDrift, Inc. Key facts: - Zero Drift Ltd, UK software studio, company 17202217 — not the US company ZeroDrift, Inc. - The studio publishes its methods, prices and delivery evidence in the linked primary pages. ## Build - [Build a complete product](https://zerodrift.co.uk/build/): Zero Drift turns a difficult business job into a complete, operated product—not a convincing first screen with the rest left to someone else. ## Refactor - [Change a live system without losing what already works](https://zerodrift.co.uk/refactor/): Modernise the software your business depends on without asking people to give up the capabilities they already use. We agree what must stay the same, replace the parts that hold you back and test the result against the existing service. ## Public sector - [Modern public-service software](https://zerodrift.co.uk/public-sector/): Complete civic applications and careful legacy modernisation, with lower build and running cost as design goals and inspectable evidence behind the service. ## Review - [Get the technical truth](https://zerodrift.co.uk/review/): An independent technical review should answer the decision in front of you, show what was tested and make its limits clear. ## Build with us - [Build with us](https://zerodrift.co.uk/build-with-us/): Zero Drift can design, build, host and run qualifying products for a share of revenue while the domain founder keeps the business and product IP. ## Fractional CTO - [Fractional technology leadership](https://zerodrift.co.uk/fractional-cto/): Named senior product and architecture leadership turns technical uncertainty into decisions the business can make and revisit. ## Rates - [Rates and how we quote](https://zerodrift.co.uk/rates/): 10 published service lines, quoted from written scope. ## Buyer decision packs - [Six buyer decision packs](https://zerodrift.co.uk/decision-packs/): Downloadable fit, price, deliverable, authority, acceptance and evidence briefs for each work route. - [Build a complete product decision pack](https://zerodrift.co.uk/decision-packs/build/): A working service, not a good-looking first screen. - [Change a live system decision pack](https://zerodrift.co.uk/decision-packs/refactor/): Replace what is broken without making users start again. - [Modernise a public service decision pack](https://zerodrift.co.uk/decision-packs/public-sector/): Keep the obligations. Lose the inherited constraints. - [Get the technical truth decision pack](https://zerodrift.co.uk/decision-packs/review/): A decision a board can make, with findings another person can reproduce. - [Build for revenue share decision pack](https://zerodrift.co.uk/decision-packs/build-with-us/): Your domain and customers. Our complete product engineering. Aligned earnings. - [Fractional technology leadership decision pack](https://zerodrift.co.uk/decision-packs/fractional-cto/): Named senior judgement, written down and available when decisions recur. ## Method - [How we build](https://zerodrift.co.uk/method/): Spec-first delivery, explicit gates and evidence-backed handover. - [Utility, not SaaS](https://zerodrift.co.uk/method/anti-saas/): The utility economics behind complete, cheap-to-run software. - [The deterministic gap](https://zerodrift.co.uk/method/determinism/): Where inference ends and the deterministic system begins. ## Products - [Phoenix Ember](https://zerodrift.co.uk/products/ember/): Inclusion-first assessment, intervention and evidence software for schools. - [Phoenix Nest](https://zerodrift.co.uk/products/nest/): A management information system designed around the work a school actually does. - [Phoenix Eyrie](https://zerodrift.co.uk/products/eyrie/): Statutory SEND and EHCP case management for local authorities. - [Phoenix Flight](https://zerodrift.co.uk/products/flight/): Post-16 software built around learner progress and support. - [Quorate](https://zerodrift.co.uk/products/quorate/): Governance software for clubs, councils and membership organisations—the meeting, the work between meetings and the evidence behind decisions. - [ClarityCrowd](https://zerodrift.co.uk/products/claritycrowd/): Complete core HR for employers, growing into career development and objectives that connect people’s work to business outcomes. - [SelfFiled](https://zerodrift.co.uk/products/selffiled/): A calm annual tax utility for individuals and small businesses, from bookkeeping to retained filing history. - [Certifitrades](https://zerodrift.co.uk/products/certifitrades/): Trade compliance paperwork ready to share—cards, certificates and insurance, with reminders before they expire. - [TenantTidy](https://zerodrift.co.uk/products/tenanttidy/): A landlord’s property record for certificates, tenant serves, deposits and rent, with an exportable compliance pack. ## Papers - [Papers](https://zerodrift.co.uk/papers/): Dated, attributable papers on verification, delivery and software economics. - [Compile the specification](https://zerodrift.co.uk/papers/compile-the-specification/): AI can reduce the effort of producing code, increasing the relative importance of resolving ambiguity before implementation. Specification-driven development turns business intent into versioned schemas, state, contracts and executable acceptance evidence before agents multiply the wrong assumption. - [The depth signature](https://zerodrift.co.uk/papers/depth-signature/): A feature is not complete because its happy path renders. Its required depth depends on the system it changes. This paper defines a risk-shaped signature for testing security, data, concurrency, recovery, performance, accessibility and operations at the right level. - [The deterministic gap](https://zerodrift.co.uk/papers/deterministic-gap/): Generative AI can propose, explain and build at extraordinary speed. It still cannot make a consequential answer true. This paper separates inference from computation and argues for systems in which models expand the option space while explicit rules, state and evidence close it. - [Five laws of agentic delivery](https://zerodrift.co.uk/papers/five-laws-agentic-delivery/): Agentic engineering fails when a persuasive session is mistaken for a delivery system. Five operating laws turn model capability into controlled production work by moving plans, units, depth, model choice and parallelism into inspectable artefacts and gates. - [The local AI workstation](https://zerodrift.co.uk/papers/local-ai-workstation/): Frontier cloud models and controlled local models are complements. Use scarce frontier reasoning to compile specifications and resolve ambiguity; use open-weight models on owned or rented hardware for bounded engineering roles, with harnesses and CI/CD gates deciding what survives. - [Metamorphic oracles](https://zerodrift.co.uk/papers/metamorphic-oracles/): AI may reduce the cost of authoring and maintaining behavioural challenges, giving teams reason to reassess the economics behind the test pyramid. Metamorphic relations, mutation and system-level observation can turn tests from examples of success into an adversarial evidence system. - [Utility economics](https://zerodrift.co.uk/papers/utility-economics/): Software construction and operation are becoming cheaper, but much of SaaS still prices scarcity, lock-in and feature withholding. This paper argues for complete products sold like dependable utilities: low-friction, fairly margined and valuable because they work, not because leaving hurts. - [Zero-divergence refactors](https://zerodrift.co.uk/papers/zero-divergence-refactors/): Legacy replacement does not require a cut-down successor and a decade of feature-parity work. If behaviour can be observed, specified and challenged, a modern system can be built behind an equivalence boundary and moved into service without forgetting its users. ## Writing - [Writing](https://zerodrift.co.uk/writing/): Field notes on products, evidence and delivery. - [Eight properties to challenge a “complete” build](https://zerodrift.co.uk/writing/an-eight-property-review-you-can-challenge/): A practical starting rubric for finding work hidden behind a polished interface, and why each property needs a check that can fail. - [How this site is checked](https://zerodrift.co.uk/writing/how-this-site-is-checked/): The website itself is a useful test of Zero Drift's claim that specifications, mechanical gates and human judgement belong together. - [The session card is not a prompt trick](https://zerodrift.co.uk/writing/the-session-card-is-not-a-prompt-trick/): A bounded AI build session works because the substance and failure-capable checks are on disk, not because the instruction sounds strict. - [Which Zero Drift?](https://zerodrift.co.uk/writing/which-zero-drift/): Zero Drift Ltd in the UK and ZeroDrift's US AI enforcement business share a similar name; the entities and services are different. - [Why “staging” is on the product card](https://zerodrift.co.uk/writing/why-staging-is-on-the-product-card/): A working demonstration is useful evidence, but it is not the same as a live service or paying adoption. - [Why our rate card is public](https://zerodrift.co.uk/writing/why-the-rate-card-is-public/): The price is not a secret weapon. A buyer should know the commercial shape before spending a meeting discovering it. ## About - [About Zero Drift](https://zerodrift.co.uk/about/): The studio, its founders and the standard behind complete product delivery. - [Daniel Johnson](https://zerodrift.co.uk/about/daniel/): Zero Drift co-founder working across product direction, technical leadership and AI-assisted delivery, with prior CTO and digital-platform roles. - [Gary McLean Hall](https://zerodrift.co.uk/about/gary/): Zero Drift co-founder and architecture lead, bringing senior architecture review and regulated-platform experience to complete product delivery. ## Trust - [Trust and procurement](https://zerodrift.co.uk/trust/): Company details, security posture, insurance and legal information. - [Accessibility of this website](https://zerodrift.co.uk/legal/accessibility/): Zero Drift's accessibility approach, test scope, known limits and direct feedback route for zerodrift.co.uk. - [Cookies and browser storage](https://zerodrift.co.uk/legal/cookies/): What this site stores in a visitor's browser, including colour preference, referral details, Cloudflare analytics and form protection. - [How an engagement is agreed](https://zerodrift.co.uk/legal/terms/): A plain-language summary of Zero Drift's fixed-scope, retainer and revenue-share commercial routes; the signed agreement governs each job. ## Contact - [Contact Zero Drift](https://zerodrift.co.uk/contact/): Quotes: quotes@zerodrift.co.uk; product partnerships: partners@zerodrift.co.uk; general enquiries: enquiries@zerodrift.co.uk; security: security@zerodrift.co.uk; press: press@zerodrift.co.uk.