Search
Press / from anywhere to search across every product, doc and API reference, so developers can jump straight to what they need.
Sage
2023–2025
Building Sage's developer experience from scratch
Designing Sage’s developer portal, documentation, API reference and design system as the team’s only designer.
Outcome
A foundation for partners and product teams
26 products, one portal
Brought 26 Sage products into a single developer portal, grouped by business size and filterable by region.
640+ documented operations
Designed an API reference that scales: the Embedded Accounting REST reference alone documents over 640 operations, with search and light/dark mode.
Trusted by partners
The portal showcases what partners like Tide, Monzo and ANNA have built on Sage.
“
Mark is approachable and happy to walk through things. His knowledge of development, and how closely he collaborates, really helps take a design into production.
Jon Burger
Partner Digital Experience Manager
Introduction
A clearer path to the first API call
Developers needed a clear way to understand Sage’s APIs and make their first API call. When I joined, there was no complete developer experience to guide them.
A new team rebuilt it from scratch. As the only designer, I worked across the brand, landing pages, documentation, API reference, console and design system.
Key decisions
The calls that shaped the portal
1. Every product follows one structure.
Sage is a very large org with lots of products, teams and a complex structure. I designed one template for every product (Overview, Docs, API, Announcements and Status), so developers learn the portal once. The template was flexible and I provided building blocks for the teams to customise the pages the way they wanted but within the constraints I provided.
Result: Developers learn the portal once, and product teams customise inside the same template rather than inventing a new page type.
2. Search comes before navigation.
With 26 products and over 640 API operations in Embedded Accounting alone, no menu could hold it all. I made search reachable from anywhere with the platform-agnostic “/” shortcut, covering products, docs and the API reference.
Result: Developers can jump straight to any guide or endpoint from any page, without learning the navigation.
3. One set of tokens for light and dark.
Developers expect dark mode, and docs pages full of code samples have to work in both themes. I built the design system on one set of tokens so every page, doc and code sample switches cleanly. This took some up-front time investment, but it was something we committed to as a team.
Trade-off: It took up-front time, but the team committed to one token set so every page, doc and code sample switches cleanly.
4. Make the portal the source of truth.
I designed the portal so anything on it is shippable today, and aligned the product page wording with sage.com and the docs.
Result: The portal is the shared reference for what is ready to ship.
What I’d do differently
In hindsight I wish I’d understood just how important the experience would be for Sage. I didn’t get to stay on the project for as long as I’d hoped, and I wish I’d been more rigorous about how the design system should be used, because once things are launched they’re much harder to change.
Designs
From the portal homepage to API documentation
REST API reference
A reference built to scale. The Embedded Accounting API alone documents over 640 operations, with clear navigation, endpoint detail and code samples side by side.
Product pages
Every product follows the same structure (Overview, Docs, API, Announcements and Status), so developers learn the portal once and it works everywhere.
Light and dark mode
Full light and dark themes built on one set of design tokens, so every page, doc and code sample works in both.
Testimonial
Feedback from the team
“
On search, Mark pushed past what the Sage design system allowed, then trusted us to iterate. When something couldn’t ship as designed, he simplified it so we could still ship.
Chris Catt
Engineering Team Lead
“
Mark is approachable and happy to walk through things. His knowledge of development, and how closely he collaborates, really helps take a design into production.
Jon Burger
Partner Digital Experience Manager
“
Mark delivers high-quality work, asks for feedback, and stays calm in difficult meetings. He’s a real asset to the team.
Andy Wilson
Principal Architect
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