Free builds: terms

Effective 2026-09-29

The details follow. If anything is unclear, email hello@numberandreason.com.

1. What we build, and the queue

• Chrome browser extensions (Manifest V3) only, for now.
• Strictly in order of confirmation, starting one a week. You can check your place any time with the link in your confirmation email; it only moves up.
• Claimable opportunities come from our public daily opportunity list, and each goes to one person: whoever confirms first.
• If you bring your own idea, we first run a free verdict. We build only if it comes out worth building; if not, you get the verdict document and the reasons.

2. Assessment and scope

• When it's your turn, we assess the features. If we can't take it on, we'll write to you with the specific reasons and how you could adjust it to apply again.
• Once it passes, we confirm the features with you and see it through to launch.
• The building is mostly done by AI; we review and test it.

3. What you receive

• All source code, and a packaged extension ready to upload to the store.
• Store listing text, screenshot materials, and a privacy policy template written for what the extension actually collects (you check it before use).
• Help submitting for review, and changes the review asks for, until it's live.
• Handover notes: how to make changes and ship new versions.

4. Ownership and accounts

• The extension, its code, the store listing, the developer account and the extension's users are all yours.
• You submit from your own Chrome developer account. We never log in to or operate your account, and we never need any of your passwords.
• The store doesn't allow the same developer or affiliated accounts to publish near-duplicate extensions, so we won't build an extension with the same function as yours for anyone else. If the opportunity you claim is too close to one we're building ourselves, we'll tell you before we start.
• We may reuse generic code and techniques (the parts unrelated to your extension's function) in other projects.

5. A month of maintenance

• For a month after launch we fix, free of charge, anything that stops the extension working (for example a target site changing, or changes the store asks for).
• New features aren't part of maintenance; you can submit them as a new request.
• After that month you maintain it yourself; the handover notes explain how.

6. Costs

Everything is free: assessment, building, help with review and a month of maintenance, including the AI costs of building it. The only outside cost is Google's developer registration fee (one-time US$5), which you pay to Google directly.

7. Data sharing and the public case study

• For 90 days after launch, please export your Chrome developer dashboard statistics (impressions, installs, uninstalls and so on) once a week and send them to us. We use them only to validate our opportunity-finding method and to write the case study; we never sell them or pass them on.
• We write up the journey, from claiming the opportunity through research, building and review to the numbers after launch, as a public case study. You can stay anonymous: we leave out your name, and you decide whether the extension is named.
• We never access personal data of the extension's users.

8. When we stop

• You don't reply to our emails for 14 days in a row.
• The requested features break store policy or the law (cheating, cracking, bypassing paywalls or detection, for example).
• The agreed data isn't shared: what's delivered stays yours, but maintenance ends.
• The opportunity you claimed was confirmed by someone else first.

If we stop, you still get whatever is already built.

9. Responsibility

• Google decides store review; we make the changes the review asks for but can't guarantee approval.
• You are the publisher and are responsible for the extension, its privacy policy and user support.
• This is a free service. Except for liability that can't be excluded by law, we aren't liable for indirect losses from using the extension.

10. Changes and contact

If these terms change, we update the effective date on this page; builds already started follow the terms in force when they started. How we handle your application details is in the privacy notice.

Number & Reason (Hangzhou) Digital Technology Co Ltd · No. 138 Hutangxia, Chengbei SME Incubation Base, Xishu Community, Jinbei Subdistrict, Lin'an District, Hangzhou, Zhejiang Province, China · hello@numberandreason.com