London software developer Letter Assembly raises £1.3m seed round

London-based software developer Letter Assembly has secured an estimated £1.3m in a seed funding round. The company specializes in business and domestic software development and has been active since its incorporation in March 2025.

This latest investment follows a series of funding events recorded over the first year of the company's operations. In April 2025, shortly after its founding, the firm raised £2.5m at a valuation of £10.3m. This was followed by a £165k raise in June 2025, which carried a valuation of £10.5m.

The company's valuation rose from £10.5m in mid-2025 to £42m by January 2026. During January, Letter Assembly completed a pre-seed round of £171.8k at a £42m valuation and a £5.5m Series A round at a £41.8m valuation. The current £1.3m seed round (allotted in April and filed in May) brings the total capital raised by the firm to approximately £9.6m across five transactions.

Letter Assembly focuses on the development of software for both commercial and domestic use. While specific financial metrics such as annual revenue, employee headcount, and profit or loss figures are not publicly available, the company has maintained a consistent pace of fundraising since its inception. The firm continues to operate from its headquarters in London, addressing requirements within the software development sector.