We build our own software. And yours.
Celsa is a small, founder-led studio in London. We make products like ColdSoup, and we build websites and software for businesses at prices that make sense for a small business.
- Websites
- Web apps
- Online stores
- Internal tools
- AI features
- Integrations
One studio, two kinds of work.
Running our own products keeps us honest about what it takes to ship and support real software. Client projects get the same care.
Software we build and run ourselves.
We design, ship and support our own products. The first is ColdSoup, an AI-native office suite for teams.
Our products ServicesWebsites and software, built for you.
From a one-page site to a small web app, we take it from the first call to launch and look after it afterwards.
Services and pricesWe design and build websites
Design
Layouts and interfaces worked out properly, from rough sketches to a prototype you can click through.
Websites
Fast, responsive sites with sensible SEO and content you can edit yourself.
Web applications
Booking systems, portals, dashboards and tools, shaped around how your team works.
Online stores
Shops with a quick checkout, card payments and order emails that just work.
AI features
Assistants, search and automation added where they save real time, and left out where they don't.
Care and hosting
Updates, backups and small changes each month, so the site keeps working after launch.
An office suite with the AI in the room.
Docs, slides, sheets, chat and a calendar in one shared room, with an AI helper on every page. Start a room, send the link, and your team is in. There's no sign-up and nothing to install.
- Edit together live and see who wrote what
- The AI helper works in the open, and any edit it makes can be undone
- Join from any browser with a room code or link
What projects cost.
Small-business prices, and a fixed written quote before any work starts. Nothing we offer goes above £3,000.
- Landing siteA one-page or small site, live in a week or two.from £450
- Business websiteA proper multi-page site you can update yourself.from £950
- Online storeA shop with card payments, stock and order emails.from £1,500
- Web appA booking system, client portal or internal tool.from £2,200
- The Software HandbookOur printed guide to how software is put together.£24
Not ready for a project? Start with the book.
The Software Handbook is our printed, plain-English guide to how software is structured: front ends, back ends, databases, APIs, hosting and security. Written for founders and teams who want to understand what they're paying for.
Tell us what you're building.
A few lines is plenty. We aim to reply within one working day, and if we're a good fit you'll get a fixed quote.