Sentry.io - From error tracking to performance monitoring, developers can see what actually matters, solve quicker, and learn continuously about their applications - from the frontend to the backend.
strace - Trace system calls and signals. A diagnostic, debugging and instructional userspace utility.
LiveSession - LiveSession helps you analyze users’ behavior, improve UX, find JS bugs, and increase conversion rates using session replays, and event-based product analytics.
ftrace - A function tracer for the Linux kernel.
Hotjar - The #1 Leader in Heatmaps, Recordings, Surveys & More. Sign up for a 15-day free trial and start learning from real user behavior today!
Valgrind - Valgrind is an instrumentation framework for building dynamic analysis tools.