Twilio Changelog | Jul. 10, 2025
Twilio Functions Add Real-Time Concurrency Insights via Response Headers
We know how important it is for developers to understand what’s happening under the hood, especially when things get busy. That’s why we’ve added a new way to keep an eye on your Twilio Functions. Starting today, every Function response now includes a header called x-twilio-function-concurrency. This header shows you exactly how many of your Functions are running at the same time, right when you get the response.
Why does this matter?
Think of it as a quick window into your serverless traffic, with some nice benefits:
Current concurrency at your fingertips: Get a quick, per-request snapshot of how many Functions are running right now. No additional reporting or querying required.
Build smarter, load-aware retry logic: Use the concurrency value in your code to adjust retries or introduce backoff as things get busy. This can help you avoid hitting rate limits (like 429 errors) and keep your app resilient. Just note, you’ll want to update your code to take full advantage of this data.
Integrate with your monitoring: Feed the header value into your preferred monitoring or alerting tools to stay informed about spikes and trends as they happen.
Better planning: Spot patterns in how your Functions are used, making it easier to scale, optimize, or decide when to break up workloads.
Confidence in testing: When you run load tests, you’ll instantly know how your Functions handle the pressure.
This is a small change that packs a punch when it comes to transparency and reliability. While you don’t need to make changes to start seeing the new header, you’ll want to update your code or workflows if you’d like to automate responses, retries, or alerting based on this live concurrency data.
Need a hand?
Check out our Twilio Functions & Assets FAQs for all the details.
Thanks for building with Twilio. We can’t wait to see how you put these new observability tools to work!
– Team Twilio