The screen the whole salon day runs through
The Calendar is the operational core of Treatwell’s platform. Partners open it in the morning and stay in it all day, and it is the surface that drives daily engagement with the product.
It also carried years of front-end history. Legacy UI patterns and accumulated technical debt made features hard to find, slowed the onboarding of new partners, and turned every change into a regression risk.
That cost showed up on both sides. Partners worked around the interface. Product and engineering paid for every release in review time and caution.
A calendar thousands of salons depend on cannot be taken offline for a rebuild.
New architecture beside the old interface
We rebuilt the Calendar front-end on React through an incremental migration. The new architecture went in gradually and stayed compatible with the existing interface, so partners kept working while it happened.
Start where the day happens
Calendar scheduling and employee availability first. The two features partners use every day, and the two that carried the most debt.
Keep both worlds working
New React components run next to the existing interface. Nothing had to be switched off for the migration to start.
Restructure, not reskin
A cleaner component structure, a clearer information hierarchy, and a firm separation of concerns. Less coupling, fewer surprises.
Migrate feature by feature
Each step small enough to verify and to reverse. No big-bang release on the surface partners depend on.
Three shifts that make the next feature cheaper
Component structure
Calendar behaviour lives in components with clear boundaries, so a change stays where you made it.
Information hierarchy
What a partner needs during a busy day comes first. Features that used to hide are now where you look for them.
Separation of concerns
Data, state and presentation are pulled apart. Less coupling means less regression risk on every release.
Features shipped, foundation left behind
Two core features rebuilt, and a front-end Treatwell’s own teams can keep building on.
Calendar scheduling
Rebuilt in React, with the booking flows partners run dozens of times a day.
Employee availability
Managing who works when, on the same new architecture as the calendar itself.
Migration path
New and existing interface side by side, with a route for the features that follow.
Front-end foundation
Component patterns and boundaries the product teams keep working in after we hand over.
Front-end engineers inside the product team
We work in Treatwell’s squads, on Treatwell’s roadmap. On this one we also argued for the incremental route over the rewrite.
Senior front-end engineering
Engineers who have migrated live interfaces before, embedded with the team that owns the Calendar.
Incremental migration playbook
How to introduce new architecture next to old, what to move first, and how to keep every step reversible.
More of our work
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A front-end you cannot take offline?
Tell us which screen your users live in and what it costs you to change it. We will tell you what a migration looks like that they never notice.