Best Sentry JavaScript Error Monitoring Alternatives & Competitors in 2025

Fiddler is a debugging program for websites.

Firefox JavaScript Debugger is a rich-functional website monitoring tool that provides you an opportunity to step through JavaScript code and test or modify its state, helping in tracing the bugs from all over the network.

Ensure healthy website performance, uptime, and free from vulnerabilities. Automatic checks for SSL Certificates, domains and monitor issues with your websites all from one console and get instant notifications on any issues.

Try for free freemium $9.0 / Monthly (Lite plan)

Deployment, Defacement, & Security Monitoring

Firefox Page Inspector is a multi-featured tool that allows you to navigate through the components that go into rendering their pages, enabling you to achieve better performance, find bugs and check mobile views, and many others.

Inspect Element is a multi-functional tool that is introduced to get information about what makes the web tick, figure out what is broken in your sites, and mock-up what a specific color or font change would look like.

TypeScript allows developers to compile a superset of JavaScript to plain JavaScript on any browser, host, or operating system.

Open Source

Firebase is a cloud service designed to power real-time, collaborative applications for mobile and web.

Jan 1, 2018 - A powerful replacement for the macOS / OS X Terminal, with 24-bit color and graphics features.

Open Source

Enhanced terminal for Windows with X11 server, tabbed SSH client, network tools and much more

Popular free terminal application. Mostly used as an SSH client.

The most advanced tools for tracking changes on websites.

Customer engagement platform used by over 1 million developers and marketers; the fastest and most reliable way to send mobile and web push notifications, in-app messages, emails, and SMS.

Open Source freemium $9.0 / Monthly (Plus usage-based costs. (Growth Plan). )

HTTP proxy / HTTP monitor / Reverse Proxy