A productised site or web app
Marketing, onboarding and the first product surface, on a stack that will still be maintainable two years later.
Next.js · UK
A Next.js development agency that shows the numbers.
Kyln builds production software on Next.js for UK founders, operators and agencies: marketing sites, web apps, portals and the hand-over from an AI prototype into something real users can run. Lab Core Web Vitals from this site, named production work, and published prices. No template filler.
Reviews from £1,500 · builds from ~£20k · care from £175/moWhen teams buy this
Past the brochure site, short of a full engineering team.
The SERP is full of thin agency pages with no metrics and no price. Four situations keep landing at Kyln instead.
An AI-generated Next.js prototype
It demos. Authentication, data, secrets and deploy do not. Someone senior has to read it and decide salvage, refactor or rebuild.
An agency after a design-ready build
The creative is signed off. Delivery still needs production-grade Next.js work under the agency brand, or under yours.
A live Next.js site with no caretaker
Updates, dependency patching and the monthly edit queue need an owner. That is a care plan, not a rebuild.
Core Web Vitals · lab
Numbers from a shipped build, not a slide.
kyln.digital is a production Next.js app on Vercel. Responses carry x-nextjs-prerender and a CDN cache hit. The Vitals below were measured on that live deploy on 13 July 2026 with Lighthouse 13.4, mobile, simulated throttling.
Lab, not field. Chrome UX Report / Search Console field data is not wired for public display yet, so these figures are not sold as real-user percentiles. They are re-runnable against the live site at any time.
| Route | Perf | FCP | LCP | CLS | TBT | TTFB |
|---|---|---|---|---|---|---|
| / | 89 | 1.2 s | 3.8 s | 0.015 | 20 ms | 13 ms |
| /fractional-cto | 95 | 1.3 s | 2.9 s | 0 | 0 ms | 15 ms |
| /pricing | 94 | 1.2 s | 3.0 s | 0 | 0 ms | 77 ms |
| /products/care | 88 | 0.9 s | 3.5 s | 0.002 | 10 ms | 14 ms |
Read them the way a performance engineer would. Document TTFB on prerendered routes sits in the low tens of milliseconds. CLS is near zero across the set. LCP on the image-heavy homepage is still the number that needs work — printed because inventing a greener figure is how thin agency pages write, and this is not that page.
What ships on Next.js
Sites, apps, rescues and the care after.
Sites that load as static HTML
App Router pages, prerendered where the content is stable, with a visible performance budget. The marketing site at kyln.digital itself is the reference: x-nextjs-prerender on the response, a Vercel edge cache hit, document TTFB in the low tens of milliseconds.
Auth, data and real deployments
Customer portals, operator tools and product surfaces on Next.js: server components for the data path, hardened API routes, a proper database and an environment that is not the developer's laptop. Built as software you can hand over and run.
v0, Bolt and Cursor → something shippable
When the first cut came out of an AI tool on a Next.js/React stack, the rescue work is the same job: real auth, a data layer that holds data, secrets off the client, and a deploy path that does not break on the second user. Review first, from £1,500.
A plan for a custom Next.js site
Hosting, SSL, backups, uptime monitoring, dependency and security updates, and a monthly block of edits — productised for custom, Next.js and AI-built sites, not just WordPress. From £175 a month.
Named production work
Outcomes on the page, not logos in a carousel.
Two public case studies carry the proof. Neither invents a stack claim that is not on the record; both put a real outcome number next to a named client.
- Spectinga — email deliverability rescue. Revenue had dropped about 30% after a provider switch. Cause found in under thirty minutes; click rate back within a week.
- Tango — document automation for an insurer, built with Ford Creative. Terms-and-conditions from months to about five minutes.
- This site — the live Next.js App Router deploy the Vitals above were measured against, with the render path and edge cache headers on every request.
Further client work is not named here until it is on the public work index with a case study. Empty beats invented.
Engagement pricing
The numbers sit on the pricing page, not behind a call.
Most Next.js agency pages stop at “get a quote”. The commercial path here is the same one already published on the rest of the site.
Review
From £1,500
Paid readiness or build-scope review. The plan and the price of the build sit on what someone senior has actually read.
Build
From ~£20k
Product and platform builds on Next.js, scoped after the review. You own the code, the site and the domain.
Care
From £175/mo
Kyln Care for custom and Next.js sites: hosting, monitoring, updates and a monthly block of edits.
Direction
From £3,000/mo
Fractional-CTO direction about a day a week — architecture, roadmap, hiring — when the build also needs steering.
Full board on the pricing page. Partner and white-label terms live on the partners page.
Next.js development questions
Want to talk through the fit? Email contact@kyln.digital
Yes. Production web work at Kyln runs on Next.js and React as a default: marketing sites, customer portals, internal platforms and the AI-prototype rescues that land on the same stack. The agency is London-based and works UK-wide.