Gaetano Franceschi
Analyst
Thank you, Andrew, and good afternoon, everyone.
First quarter revenue was $25 million, down 43% year-over-year and down 19% sequentially. Our paid user conversion rate, which is paying MAU divided by MAU, was 14% in Q1, slightly down from 15% in Q4 due to continued focus in the quarter on new user onboarding. As Andrew indicated, we are confident in our ability to continue to maintain our current payback period and begin to invest to grow sequentially.
Turning to OpEx. Research and development expense was $5 million, down 48% year-over-year. On a GAAP basis, R&D was 18% of Q1 revenue. Sales and marketing expense was $21 million, down 40% year-over-year, including $2 million of stock-based compensation. On a GAAP basis, sales and marketing was 83% of Q1 revenue compared to 79% in the year ago quarter and 75% in Q4.
Q1 UA marketing was $5.6 million, a decrease of 33% from Q1 of last year and a 3% decrease quarter-over-quarter, while Q1 engagement marketing was $8.9 million, down 50% from Q1 of last year and down 34% from Q4. General and administrative expense was $23 million, down $5 million or 18% year-over-year, inclusive of $6.6 million in stock-based compensation. On a GAAP basis, G&A was 91% of Q1 revenue.
The net loss of $27 million compares to a net loss of $36 million in Q1 2023. The adjusted EBITDA loss in the first quarter was $18 million, a 15% improvement year-over-year. Adjusted EBITDA margin was negative 70% in Q1 2024 compared to negative 47% in Q1 2023.
We continue to expect our cost structure will benefit this year from lower cost for items, including legal, audit and insurance fees as well as continued prudent management of our cost base. Additionally, interest expense will continue to decline year-over-year given the reduction in outstanding debt.
We ended the first quarter with $301 million of cash, comprised of $291 million in cash and cash equivalents and $10 million in restricted cash. As Andrew noted earlier, this does not include the $50 million received from Avia at the end of April. At the end of Q1, we had $129.7 million of total outstanding debt. With our improving cash burn, we have the flexibility to deploy capital to enhance shareholder value.
At this time, we'll turn the call to the operator for the Q&A session.