The estimated average salary for a Senior Software Development Engineer In Test at Firstbase is £67,230 per year or £32 per hour, but some professionals have reported earning up to roughly £99,181 per year (90th percentile). The typical pay range is between £55,234 (25th percentile) and £82,263 (75th percentile) annually. This is based on 1 salaries submitted by Firstbase Senior Software Development Engineer In Test professionals on Glassdoor, as of Jun 2026.