Thanks, Jonathan. Before I begin more detailed commentary on our financial results, let me first provide some clarification and quantification around the impact observed in the quarter from the contract termination Matt previously mentioned. The results of this termination were a reduction of $3.1 million in revenue related to the contract asset and outstanding receivables balance in addition to approximately $700,000 of cost of sales expenses and $160,000 of operating expenses from previously deferred commissions. As a result, the net impact is a reduction to adjusted EBITDA of approximately $3.9 million for the quarter. I will discuss our financial results and where appropriate, note the impact to our results from this termination. We are also factoring in the positive impact this development will have on our margins and our 2023 outlook, given this engagement was dilutive to our overall margin profile.
Focusing our efforts and resources on margin accretive growth opportunities is an important aspect of our outlook. As we look to optimize for profitable growth going forward. Moving to our results. We're encouraged by the continued market demand for our solutions, our booking success and the efficiencies we're driving, which are positioning us to expand margins and generate more cash flow.
Total non-GAAP revenue for the fourth quarter was $146.7 million, an increase of 11% year-over-year and up 1% sequentially. Total non-GAAP revenue for the full year was $566.3 million, up 13% from the prior year. The year-over-year and sequential increases for the quarter were primarily driven by an increase in subscription revenue associated with the deployment of new customers and continued organic growth from existing customers.
As I previously mentioned, the impact to revenue of the contract termination was $3.1 million. Our subscription revenue for the year was 73% of our total revenue, representing year-over-year growth of 14%. Based on the strength we have seen in our subscription-based bookings, we expect our subscription revenue growth will accelerate for the full year of 2023. For the fourth quarter, services revenue was in line with our expectations entering the quarter. As we discussed previously, we're continuing to monitor professional services engagements associated with projects that are more discretionary in nature. Some of which have been and could continue to be suppressed in the current macroeconomic environment.
Transactional revenue represented 11% of total revenue for the quarter, down from the prior year period of 13% and consistent with the previous quarter. For the full year of 2022, transactional revenue represented 12% of total revenue, which is down from the prior year at 14%, due in part to a decline in revenue generated from our bill pay products.
Based on the trends we're observing in our transactional business, our full year 2023 outlook anticipates the growth rate of our overall transactional revenue stream to be similar to what we observed in 2022. We added approximately 200,000 users during the quarter, ending the year with over 21.1 million registered users, an increase of nearly 2 million users or 10% year-over-year. The sequential increase was largely driven by organic user growth. The year-over-year increase was attributable to organic user growth throughout the year and new customer go-lives largely concentrated in the second half of the year.
Looking to 2023, we anticipate an increasing mix of the number of customer go-lives on our commercial banking platform as a result of the strong bookings in the second half of 2022. As we've discussed in the past, commercial go-lives carry a lower number of users compared to our retail go-lives, but also drive a higher revenue per user.
Annualized recurring revenue, or ARR, grew to $655.2 million, up 14% year-over-year from $574.2 million at the end of 2021. Our ARR growth for the year was driven largely by new and cross-sale subscription-based bookings, partially offset by a decline in transactional revenue. In addition, we observed ARR growth resulting from increasing subscription run rates associated with existing customers. ARR was also up 3% sequentially from the third quarter primarily due to booking strength observed in the fourth quarter. Our ending backlog of approximately $1.5 billion increased by $104 million sequentially or 7% and equated to a 6% increase year-over-year. The sequential increase was driven by our strongest bookings quarter of the year, across both net new and renewals. The year-over-year increase in backlog was primarily attributable to net new bookings. As a reminder, the biggest driver of changes in backlog are net new bookings and renewals. Renewals are subject to seasonality as well as the number of opportunities in Target. As a result, while it's possible we could see a sequential decline in backlog in any given quarter due to less renewal opportunities being available, we believe we will deliver year-over-year backlog growth for the full year of 2023.
Our trailing 12-month net revenue retention rate for 2022 was 110% down from 119% in 2021. Our net revenue retention rate is calculated by taking the total revenue growth in the calendar year, compared to the prior year for any customers that were implemented on any of our solutions in that prior year. The most significant drivers of change in our net revenue retention rate each year have been the number of new customers in the prior year and the timing of implementations of those new customers.
As we previously discussed, given the reduced number of go-lives, we had take place in 2021, particularly in the back half of the year, we anticipated that our rates would come down in late 2022. Our revenue churn for 2022 was 6.3%, up from 5.4% in 2021. The increase in revenue churn was concentrated within our nonfinancial institution customers, including the contract termination during the quarter, which added roughly 50 basis points to our total revenue churn. This was partially offset by a reduction in the year-over-year churn associated with our digital banking customers.
Gross margins were 51.5% for the fourth quarter and 51.6% for the full year. The contract termination negatively impacted gross margins by approximately 150 basis points for the fourth quarter and 40 basis points for the full year. This impact was partially offset by a reduced mix of lower-margin pass-through revenue and the benefits from continued productivity improvements in areas of expense reduction.
Total operating expenses for the fourth quarter were $72.7 million, or 49.5% of revenue compared to $61.5 million, or 46.5% of revenue in the fourth quarter of 2021 and $69.8 million, or 48.2% of revenue in the third quarter of 2022. The fourth quarter year-over-year increase in operating expenses as a percent of revenue was driven primarily by the onboarding of additional employees concentrated within R&D as well as sales and marketing during the first half of the year.
In addition, we saw an increase in marketing events and travel compared to the prior year period as in-person events became more prevalent coming off of COVID restrictions in the prior year. The increase in operating expenses as a percent of revenue from the previous quarter was partially driven by employee expenses associated with the acquisition of Sensibill, which took place on October 3. We ended the year with 2,249 employees, up from 2,028 at the end of 2021, with the vast majority of hiring taking place in the first half of the year.
As a result of our proactive cost measures, we observed a net reduction in headcount for the final 5 months of the year. Total adjusted EBITDA was $8.4 million for the fourth quarter and $36.9 million for the full year. The contract termination negatively impacted adjusted EBITDA by $3.9 million for the fourth quarter and full year 2022. The year-over-year and sequential change in adjusted EBITDA saw a meaningful benefit from the effective utilization of our global workforce, reduced hiring activity and lower contractor expenses as well as reduced facilities expenses. We ended the year with cash, cash equivalents and investments of $433.4 million, up from $395.7 million at the end of the third quarter. Our CapEx spend as a percentage of revenue for the full year was approximately 2%, a reduction from the 4% observed in the prior year, as we had lower infrastructure and facilities expenses. We generated cash flow from operations in the fourth quarter of $43.9 million. The strength in operating cash flow was primarily attributable to good working capital management and favorable seasonality. We also generated free cash flow of $38.4 million during the quarter.
For the full year, we generated cash flow from operations of $36.6 million and free cash flow for the full year of $6.5 million. We delivered this record performance and continued focus on higher profitability will translate into continued improvement in our cash flow conversion for the full year of 2023.
Let me wrap up by sharing our first quarter and full year guidance. We forecast first quarter non-GAAP revenue in the range of $149 million to $152 million, and full year non-GAAP revenue in the range of $632 million to $640 million, representing year-over-year growth of 12% to 13%. With the strength in subscription-based bookings in 2022, we anticipate our revenue for the full year of 2023 will have an increased mix of this higher-margin revenue stream. We forecast first quarter adjusted EBITDA of $10 million to $12.5 million and full year 2023 adjusted EBITDA of $62 million to $66 million, representing approximately 10% of non-GAAP revenue for the year.
Looking ahead, I believe we're well positioned to deliver profitable growth towards our goal of being a rule of 30 company in late 2024, which we define as a combination of total non-GAAP revenue growth and adjusted EBITDA margin. In summary, for the fourth quarter, we delivered solid revenue results and generated record operating and free cash flow for the full year, resulting in a strong balance sheet entering 2023. We feel confident in our ability to show meaningful adjusted EBITDA expansion in the years to come. With that, I'll turn the call back over to Matt for his closing remarks.