Digital planning reform has been a stated priority for successive UK governments, yet the technology underpinning most local planning authority development management functions remains fragmented, expensive, and often decades old. PlanX is one of the most significant open source responses to this challenge — a digital planning service funded by the Department for Levelling Up, Housing and Communities (now MHCLG) and built entirely in the open.

What is PlanX?

PlanX is a service that guides applicants through the pre-application and application stages of the planning process using a structured, conditional question-and-answer flow. Rather than confronting applicants with complex forms, PlanX asks plain-English questions and uses the answers to determine what consents, certificates, or prior approvals are required — and what information must accompany any submission.

“PlanX has reduced the invalid application rate at the authorities where it has been piloted by up to 30%, which translates directly into officer time saved.” — DLUHC Digital Planning Programme

The system is built on open source components throughout: a React frontend, a Node.js backend, and a PostgreSQL database. All code is published on GitHub under an open licence, meaning any authority or supplier can inspect, adapt, or contribute to it.

Which Authorities Are Using It?

PlanX has been piloted by a number of pathfinder authorities including Buckinghamshire, Lambeth, and Medway. These authorities have used PlanX to power their planning and building control portals, replacing bespoke or proprietary systems. The experience of early adopters has fed directly back into the platform’s development — a genuine example of open source collaboration in the public sector.

How Does It Connect to the Planning Data Platform?

One of PlanX’s most significant technical features is its integration with the national Planning Data platform (planning.data.gov.uk), also an open source project. PlanX queries this platform to retrieve constraints data — conservation areas, listed buildings, flood zones, Article 4 directions — automatically, rather than requiring applicants to know and declare which constraints apply to their site. This reduces errors and ensures decisions are made on accurate, nationally consistent data.

What Should Local Authorities Do?

Authorities that have not yet engaged with PlanX should monitor the MHCLG Digital Planning Programme updates and consider whether their current application portal represents good value. The marginal cost of adopting PlanX — which is free to use and actively supported — compares favourably with maintaining proprietary portals that charge per transaction or per seat.

Stuart Planner takes a keen interest in digital planning reform and the open source tools underpinning it. He is happy to discuss the landscape with planning officers and managers, and to signpost to the technical communities and implementation partners working in this space. Get in touch.