Multi-Market Site Architecture on a Single Codebase

Challenge

A home services client sells in seven metro markets. Each market needs its own phone number, its own conversion tracking, and its own local content, and the paid media team needs to route traffic into any of them without breaking attribution. The obvious approach, seven separate builds, gives you seven things to maintain and seven ways to drift apart.

Solution

We built one application serving all seven markets on their own subdomains, with the market-specific data held in a single configuration file rather than duplicated into templates. Phone numbers, addresses, service areas and local content swap by market. The harder part was attribution: a visitor from a paid ad crosses a hard redirect boundary on the way in, and query parameters do not survive that crossing unless you deliberately carry them. Lose them and the conversion still happens while the ad platform never hears about it. Detection keys off the click identifiers rather than the campaign tags alone, so it fails safe when a UTM is malformed, duplicated, or stranded after a fragment, all three of which occur in real ad traffic.

On the measurement side, one container carries market-scoped conversion tags for every market, plus a catch-all explicitly blocked by all of them so it can never double count. Every case was verified in preview before publishing, not after.

Result

Seven markets from one codebase, per-market conversion tracking that survives the paid-media entry path, and one place to make a change instead of seven. A copy correction across all seven subdomains now ships and verifies in under a minute.