The Brighton-based agency will work on optimising STA Travel’s global web platform as part of a wider overhaul of the travel provider’s online offering.
Spannerworks and iCrossing will collaborate to build regional search engine optimisation programmes in the UK and US.
Spannerworks chief executive Arjo Ghosh said: “Our experience in the travel sector is well known, but working with STA Travel has allowed us to utilise the strength of our new offering as an iCrossing company.
“This global reach gives large organisations the ability to access their online audience on a truly worldwide scale.”
The STA site acts as the online front for 450 branches in 85 countries worldwide.
STA global webmaster Craig Hepburn said: “At STA Travel we work with a web-savvy audience that needs to be able to find our information easily.
“Optimising our global online brand is one of our top priorities and Spannerworks offered both the capability and scope to achieve this.”