some businesses are not able to survive without the use of a browser extension. For many, however extensions, the extension is the core of their business. Tools such as Grammarly, Honey, MetaMask and LastPass have demonstrated they can turn into billion-dollar businesses. If your product or idea requires functionality in the browser it is essential to have a trustworthy partner who can understand both the technical issues as well as the business stakes.
At ThirdEssential We help start-ups, SaaS companies, and digital-first companies create secure, speedy and user-friendly browser extensions that function flawlessly with Chrome, Firefox, Safari and Edge.
Extensions aren’t just a matter of convenience, they’re essential for industries like:
Tools such as LastPass and Dashlane are completely integrated into the browser, processing sensitive data in a safe way.
Honey and Rakuten created their entire business around extensions that allow discounts in real-time.
MozBar along with Keywords Everywhere allow marketers to analyze online data in real-time.
Grammarly and Loom thrive due to the fact that users require quick, easy access in the browser for their functions.
MetaMask illustrates how an extension to a browser can provide access to millions of apps that are decentralized.
If your product depends on fast, seamless browser interaction, you don’t just “need an extension”—you need one that’s reliable, secure, and scalable.
We cover the entire lifecycle that extends extension creation, right from concept validation through launch and post-release assistance.
Develop custom extension for Chrome, Firefox, Safari and Edge that are compatible with your business model.
Make sure your extension is working perfectly across browsers, not breaking the performance.
Extensions are often able to handle sensitive user information. We employ encryption, sandboxing, as well as the compliance of privacy laws.
Connect to APIs or CRMs, analytics tools or payment gateways, to enhance the capabilities of your extension.
Design extensions that feel lightweight, intuitive, and non-intrusive--keeping users engaged.
Improve background scripts and caching and service workers to increase efficiency and speed.
Avoid delays that cost you money by avoiding the Google Chrome Web Store and Firefox Add-ons rejects. We can prepare extensions for you to be approved from the first day.
Extensions require regular updating to keep up with changes to browsers. We offer long-term monitoring and updates.
Add revenue streams with in-extension payments, subscriptions, or licensing. We implement Stripe, PayPal, or custom billing APIs to help you scale sustainably.
Upgrade existing extensions to Google’s latest standards. Stay compliant, keep features intact, and avoid deprecation risks.
Building a browser extension is not just about code—it’s about overcoming real business and technical barriers:
Proven Experience – Years of developing extensions for SaaS, e-commerce, and security-focused companies.
Client-First Approach – We prioritize your business goals, not just technical delivery.
Security-Driven Development – Especially critical for fintech, crypto, and productivity tools.
End-to-End Support – From concept to long-term maintenance, we’ve got you covered.
Cross-Browser Expertise – Chrome, Firefox, Safari, and Edge, all from a single codebase where possible.
We’ll test feasibility before we go to the market to ensure it’s feasible technologically and also for users’ experience.
A simple extension could take between 4-6 weeks. Integrations with complex components could take up to 3-6 months.
Yes, we create to be compliant. This helps reduce the chance of rejection.
Absolutely. We can correct bugs, add new features, or even migrate it to Manifest version 3.
We follow industry-leading practices for encryption and secure storage, a minimum of permissions, and adherence to privacy laws.
