A custom Chrome extension built around the way you work

What a Chrome extension is and when it makes sense

A Chrome extension is a small program that runs inside the browser and adds features to the pages you open. Unlike a website, it does not wait for you to visit it. Through content scripts it can read and change page content, so it can add a button to someone else’s admin panel, pull data from the page you have open, or check a form before you submit it.

It makes most sense in tools you cannot change, such as a supplier’s system, an advertising platform or an internal application. Typical uses:

• Internal tools: shortcuts and helper panels on top of systems used every day.
• Data on a page: copying details into a spreadsheet or checking values.
• Connecting systems: sending data from the page via an API to your CRM or spreadsheet.

For a standalone application with its own users and database, a custom web application is the better fit. For moving data between applications in the background, with nobody working in the browser, look at automation and integrations.

Who it suits and who it does not

It suits you if:

• you repeat the same steps on pages outside your control,
• you want an internal tool for colleagues without deploying a server or installing another app,
• you have an idea for a single-purpose browser add-on for the public.

It does not suit you if you need the feature outside Chrome, if the extension would do many unrelated things, or if it is your main product with its own accounts and user management.

How building the extension works

1. Clarifying the purpose. What exactly the extension should do, on which pages and for whom. This also determines the permissions.
2. Design. Where the controls live (popup, side panel, a button on the page) and whether an API connection is needed.
3. Development and testing directly on the pages the extension will work with, before it goes to the store.
4. Preparing for publication. Store listing, permission justifications and, if it handles user data, a privacy policy.
5. Review and publishing with the visibility you chose.

What you get

• a working extension built on Manifest V3,
• the source code and a short note on how to build and update it,
• Chrome Web Store texts, including permission justifications,
• input for the privacy policy if the extension handles data,
• help with review and publishing.

Public, unlisted, or company only

The Chrome Web Store offers three visibility levels:

• Public: anyone can find it in store search.
• Unlisted: only people with the link can install it.
• Private: only selected users, such as trusted testers, a Google Group, or your Google Workspace domain if the administrator has allowed it.

According to the Chrome Web Store documentation, all three go through the same review and follow the same policies.

What to watch out for

• Only Manifest V3 counts. As of October 2026, Manifest V2 extensions are switched off in Chrome and removed from the Chrome Web Store. An old extension has to be migrated.
• A single purpose. Store policies require one narrow, easy-to-understand purpose. Unrelated features belong in separate extensions.
• Minimal permissions. The store policies require the narrowest permissions the extension really needs. According to the review documentation, broad access to all websites makes review take longer.
• Data and privacy. An extension handling any user data needs a privacy policy, must disclose what it collects and may use the data only for the stated purpose.
• No code from a server. Manifest V3 does not allow remotely hosted code, and under the store policies the logic must be inside the package. New features therefore mean a new version, which according to the review documentation goes through the same review as a new extension.
• Third-party pages change. An extension working on someone else’s website depends on its structure. After a redesign, it may need an update.

How much a custom Chrome extension costs

Extensions have no fixed price in the price list. The indicative hourly rate in the price list is from 500 CZK/hr. The cost depends mainly on:

• how many pages and features the extension covers,
• whether it needs an API connection or its own backend,
• whether it handles personal or sensitive data (more work on permissions and privacy),
• whether it is new or a migration of an older extension to Manifest V3.

Google also charges a one-time registration fee for a Chrome Web Store developer account. For an estimate, send a short description of what the extension should do.

Frequently asked questions

Does the extension have to be in the Chrome Web Store?

Normally it is published through the Chrome Web Store, but it does not have to be publicly discoverable. Under the visibility settings, it can be installable via a link only, or limited to selected people or your Google Workspace domain.

How long does approval take?

According to Google’s review documentation, most extensions are reviewed within a few days, but it can take up to a few weeks. Review takes longer for new developer accounts, broad permissions and large code changes.

What if the company manages browser extensions centrally?

With Google Workspace or Chrome Enterprise, the administrator manages extensions in the Google Admin console. According to the Chrome Enterprise help, a private extension for the domain is visible only to users in that domain, and the administrator can also install it for users automatically.

Who owns the source code?

Ownership of the code, and which developer account the extension is published under, are agreed in advance.