Ed McGowan
Executive Vice President and Chief Financial Officer at Akamai Technologies
Thank you, Tom. I would also like to thank Tom Barth for his incredible service for 10 years as our Head of Investor Relations.
Now moving on to our results. Let me start by saying that I'm very pleased with our fiscal 2023 year results, delivering $6.20 of non-GAAP earnings per share, capping off a year of double-digit earnings growth for our shareholders. Today, I'll cover our Q4 results, provide some color regarding 2024, including some items to help investors better understand a few factors that will impact our upcoming results, and then close with our Q1 and full year 2024 guidance.
Starting with revenue. Q4 revenue was $995 million, up 7% year-over-year as reported and in constant currency. We saw continued strong growth in our compute and security businesses during the fourth quarter. Our compute business grew to $135 million, up 20% year-over-year as reported and in constant currency. We continue to be very pleased with the feedback regarding our cloud compute offerings, and we are very optimistic about the early traction we are seeing from enterprise customers.
Moving to security. Revenue was $471 million, growing 18% year-over-year and up 17% in constant currency. Our security revenue continues to be driven by strong growth in our Guardicore segmentation solution and our industry-leading web app firewall, denial of service and bot management solutions. In addition, and as Tom mentioned, we are encouraged by the early traction of our new API security solution. During the fourth quarter, we signed 17 API security customers, including four with annual contract values in excess of $500,000 per year.
Our delivery revenue was $389 million, including approximately $20 million from the contracts we recently acquired from StackPath and Lumen. International revenue was $479 million, up 8% year-over-year or up 6% in constant currency, representing 48% of total revenue in Q4. Finally, foreign exchange fluctuations had a negative impact on revenue of $4 million on a sequential basis and a positive $6 million benefit on a year-over-year basis.
Moving to profitability. In Q4, we generated strong non-GAAP net income of $263 million or $1.69 of earnings per diluted share, up 23% year-over-year or 22% in constant currency and $0.07 above the high end of our guidance range. These stronger-than-expected EPS results were driven primarily by continued progress on the cost-saving initiatives we have previously outlined and approximately $6 million in lower-than-expected transition services or TSA costs associated with the StackPath and Lumen contracts as our services organization migrated the customers onto our platform much faster than we expected.
Q4 CapEx was $143 million or just below 15% of revenue. We were very pleased with our continued focus on lowering the capital intensity of our delivery business. This effort, along with our very strong profitability, enabled us to deliver very strong free cash flow results in Q4.
Moving to our capital allocation strategy. During the fourth quarter, we spent approximately $55 million to buy back approximately 500,000 shares. For the full year, we spent approximately $654 million to buy back approximately 8 million shares. We ended 2023 with approximately $500 million remaining on our current repurchase authorization. Going forward, our intention is to continue buying back shares to offset dilution from employee equity programs over time and to be opportunistic in both M&A and share repurchases.
Before I move on to guidance, there are several items that I want to highlight in order to give investors some greater insight into the business. The first relates to our delivery revenue. In the first half of 2024, seven of our top 10 CDN customers' contracts come up for renewal. As we've discussed in the past, this type of renewal generally leads to an initial drop in revenue. And then we typically see revenue grow again as traffic increases over time. We have factored the expected outcome of these renewals into our Q1 and full year 2024 guidance.
In addition, as Tom mentioned, we plan to continue to optimize our delivery business by focusing on how we charge certain high-volume traffic customers for their usage on our network, all with an eye on profitability. For example, we plan to start charging a premium for higher cost delivery destinations. We expect to continue to optimize the ratio of peak to day-to-day traffic, and we plan to negotiate different pricing for API traffic versus download traffic. Choosing to shed some less profitable traffic will result in a more balanced and profitable approach to pricing, which we believe is the right strategy for the company.
Second, OECD member countries continue to work toward the enactment of a 15% global minimum corporate tax rate. And in particular, in December 2023, the Swiss Federal Council declared the rules in effect for Switzerland beginning in 2024. As a result, we anticipate that our non-GAAP effective tax rate will increase by roughly 1.5 to 2 percentage points to approximately 18.5% to 19%. We estimate this increase in our tax rate will have a negative impact on Q1 non-GAAP EPS of approximately $0.02 to $0.03 per diluted share and a negative impact on full year non-GAAP EPS of approximately $0.12 to $0.15 per diluted share. The impact of this tax rate change has been factored into our Q1 and full year 2024 guidance.
Third, we expect to generate significantly more free cash flow in 2024 compared to 2023 levels. This is primarily due to much lower capital expenditures in 2024, along with our continued focus on profitability. Please note that the full cost to build out our Gecko compute sites we announced earlier today is included in our Q1 and full year 2024 capital expenditure guidance.
Fourth, I want to remind you of the typical seasonality we experienced on the top and bottom lines throughout the year. Regarding revenue, the fourth quarter is usually our strongest quarter. Regarding profitability, in Q1, we incurred much higher payroll taxes related to the reset of social security taxes for employees who maxed out during 2023 and from stock vesting from employee equity programs, which tend to be more heavily concentrated in the first quarter. It's also worth noting that in Q3, our annual company-wide merit-based salary increases go into effect, so we tend to see higher operating costs in Q3 compared to Q2 levels.
Finally, for 2024, we anticipate heightened volatility in foreign currency markets driven by the unpredictable timing and magnitude of Federal Reserve policy changes and their impact on interest rates. With this in mind, forecasting the trajectory of FX in the latter part of the year poses a formidable challenge. Thus, for the full year, we plan to provide annual revenue growth, security and compute revenue growth, non-GAAP EPS growth, non-GAAP operating margin and CapEx only in constant currency, based on 12/31/2023 exchange rates. However, for the coming quarter, we will provide both as reported and constant currency guidance.
As a reminder, we have approximately $1.2 billion of annual revenue that is generated from foreign currency with the euro, yen, Great British pound being the largest non-U.S. dollar sources of revenue. In addition, our costs in non-U.S. dollars tend to be significantly lower than our revenue and are primarily in Indian rupee, Israeli shekel and Polish zloty.
Moving now to guidance. Our guidance for 2024 assumes no material changes, good or bad, in the current macroeconomic landscape. For the first quarter of 2024, we are projecting revenue in the range of $980 million to $1 billion or up 7% to 9% as reported or 8% to 10% in constant currency over Q1 2023.
At current spot rates, foreign exchange fluctuations are expected to have a positive $2 million impact on Q1 revenue compared to Q4 levels and a negative $4 million impact year-over-year. At these revenue levels, we expect cash gross margin of approximately 73% as reported and in constant currency. Q1 non-GAAP operating expenses are projected to be $305 million to $310 million. We anticipate Q1 EBITDA margins of approximately 42% to 43% as reported and in constant currency. We expect non-GAAP depreciation expense of $127 million to $129 million. We expect non-GAAP operating margin of approximately 29% to 30% as reported and in constant currency for Q1. And with the overall revenue and spend configuration I just outlined, we expect Q1 non-GAAP EPS in the range of $1.59 to $1.64 or up 14% to 18% as reported and 16% to 19% in constant currency. This EPS guidance assumes taxes of $56 million to $58 million based on an estimated quarterly non-GAAP tax rate of approximately 18.5% to 19%. It also reflects a fully diluted share count of approximately 155 million shares.
Moving on to CapEx. We expect to spend approximately $146 million to $154 million, excluding equity compensation and capitalized interest in the first quarter. This represents approximately 15% of total revenue.
Looking ahead to the full year for 2024, we expect revenue growth of 6% to 8% in constant currency. We expect security revenue growth of approximately 14% to 16% in constant currency. We expect compute revenue growth to be approximately 20% in constant currency. And we are estimating non-GAAP operating margin of approximately 30% in constant currency. And full year CapEx is expected to be approximately 15% of total constant currency revenue, which again includes the Gecko compute build-outs.
We expect our CapEx to be roughly broken down as follows: approximately 3% of revenue for our delivery and security business, approximately 4% of revenue for compute, approximately 7% of revenue for capitalized software and the remainder for IT and facility-related spend. We expect non-GAAP earnings per diluted share growth of 7% to 11% in constant currency. And as we mentioned earlier, this non-GAAP earnings guidance is based on a non-GAAP effective tax rate of approximately 18.5% to 19% and a fully diluted share count of approximately 155 million shares.
In closing, we are very pleased with the strong finish to 2023. We continue to be excited about our growth prospects and driving profitability across the business.
Now Tom and I would like to take your questions. Operator?