While it is now common to develop web or mobile apps with AI, the creation of Chrome extensions remains surprisingly under-exploited.
While it is now easy to ask an AI to generate code on the fly, designing an application from A to Z still requires specialized agents (Claude Code, Gemini CLI, Codex, etc.). But that’s without counting on Anthropic. The San Francisco start-up has deployed within its chatbot a sandboxed execution environment capable of issuing commands but also, more interestingly, of creating files. (Even though ChatGPT also has a container, its overall autonomy and final results are much less clean than those of Claude, according to our tests.) It is thus possible to generate a complete compressed archive containing several files. A capability that allows you to quickly create a Chrome extension, which is nothing other than a folder grouping several JS code files. The possibilities are vast and still little exploited.
How to create your extension with Claude in 2 prompts
To create your Chrome extension, simply log in with a (free) account at Claude.ai and ask the AI to guide you step by step (example prompt below). A paid plan is not necessary to create a simple Chrome extension. On the other hand, if you want to add a layer of complexity, it will be necessary to have a Pro account to access Claude Opus 4.6, the best proprietary code model on the market, which will provide even more precise code without spending hours debugging.
To develop your Chrome extension, you will only need two prompts: the first to present your needs to the AI, the second to answer the additional questions it will ask you in order to refine the specifications. Once all the information is in his possession, Claude develops each file one by one and produces, at the end, a compressed archive in ZIP format.
For the test, we will build a tweet generator based on our likes. The principle: when a tweet is liked, the AI offers two to three sentences of comment sparking interaction with the original post, at the time of re-sharing. The generated tweet must therefore contain two to three catchphrases and a link to the original tweet.
We use the following prompt template:
Tu es un expert senior en développement d'extensions Google Chrome (Manifest V3). Tu maîtrises parfaitement l'architecture des extensions Chrome (background service workers, content scripts, popup, options page, storage API, permissions, etc.), ainsi que les bonnes pratiques de sécurité, de performance et de design UI/UX. Voici comment nous allons travailler ensemble : Phase 1 — Briefing & Cadrage Je vais te décrire ma mission avec ses contraintes. Avant de coder quoi que ce soit, tu devras me poser 4 à 5 questions complémentaires pertinentes pour lever toute ambiguïté. Ces questions doivent couvrir les aspects suivants si je ne les ai pas précisés : Le périmètre fonctionnel exact (ce que l'extension doit faire ET ne pas faire) Les sites ou contextes ciblés (toutes les pages, un domaine spécifique, etc.) Les préférences UI/UX (popup, sidebar, injection dans la page, thème clair/sombre…) Les contraintes techniques (APIs tierces, stockage local vs sync, permissions sensibles…) Le public cible et le niveau d'expérience utilisateur attendu Phase 2 — Architecture & Validation Une fois mes réponses reçues, tu me présenteras : L'arborescence complète des fichiers du projet Un résumé technique de l'architecture choisie (quels composants, quel flux de données) La liste des permissions Chrome nécessaires avec justification pour chacune Tu attends ma validation avant de passer au code. Phase 3 — Développement fichier par fichier Tu construiras chaque fichier un par un, dans l'ordre logique : manifest.json Fichiers HTML (popup, options…) Fichiers CSS Scripts JS (background, content scripts, popup logic…) Assets (icônes, images si nécessaire) Pour chaque fichier, tu ajouteras des commentaires clairs dans le code expliquant la logique. Phase 4 — Livraison A la fin, tu regrouperas tous les fichiers dans une archive .zip prête à être chargée dans chrome://extensions en mode développeur. Tu me fourniras également un bref guide d'installation en 3 étapes. Contraintes générales à respecter : Manifest V3 obligatoire (pas de V2) Code propre, modulaire et maintenable Aucune dépendance externe sauf si explicitement demandé UI minimaliste et responsive Gestion d'erreurs robuste avec messages utilisateur clairs.
All that remains is to install it in Google Chrome.
Install the extension created in Chrome
To install the Google Chrome extension, nothing could be simpler. Go to Google Chrome, then type chrome://extensions/ in the address bar. Then enable “Developer Mode” at the top right. Once this mode is activated, the “Load Unpacked” option appears. Click on it and select the directory of the extension you just unzipped. And… that’s it. The extension is now integrated into your Chrome. Be careful, however: if you change devices, you will have to re-import the unpackaged extension, because synchronization is not automatic between devices.
Multiple and often underestimated use cases
Beyond this specific example, the development of Chrome extensions remains largely underestimated. Many users favor the creation of web applications or classic apps while the Chrome extension has real advantages for automating daily tasks. Unlike a web app which requires hosting, a backend and requires the user to change context, the extension is integrated directly into the work environment. It’s always there, available in one click, without friction. The Chrome extension, or other, becomes a tailor-made tool that is activated precisely when it is needed.
No need for complex infrastructure to maintain, no servers to configure, no friction for the end user. The extension directly accesses the content of web pages, can manipulate content in real time, store data locally and integrate with the APIs of visited sites. It triggers in the right context, at the right time, without the user having to think about launching an external application. For teams, internal distribution is very simple: a zip file is enough. With Claude now generating clean, working code in minutes, developing a custom extension has never been easier.
