Privacy Policy

Who we are

BuildOn Marketplaces is operated by Twenty Three Systems LLC, 8 The Green, Dover, DE 19901, United States. It runs the AI Builder Residency, the BuildOn Marketplaces mini app, this website, and our advertising landing site at lineappbuilders.com. This policy covers all of them. It explains what personal data we collect, why, and what we do with it. Twenty Three Systems LLC is the data controller for that information.

The residency is delivered in person in Taichung, Taiwan, at a venue to be announced, and live online.

Questions or requests about your data: privacy@buildonmarketplaces.com.

What we collect

From LINE, when you use the mini app

When you open our mini app inside LINE, or add our LINE Official Account as a friend, we receive from LY Corporation:

• Your LINE user ID — an identifier specific to us. It is not your phone number and cannot be used to contact you outside LINE.
• Your LINE display name.
• Your LINE profile picture.
• Your language setting.

We do not receive your email address, phone number, real name, LINE password, contacts, or message history. We cannot read your LINE conversations.

From you, when you apply

Inside the mini app:

• Your answers to the application questions — what you have built, what you want to build, who it is for, and your availability.
• Anything you choose to include in those answers, such as links to your work.

If you apply through one of our websites instead of inside LINE, we also collect:

• Your name and email address, so we can reply to you.
• Which of our sites you applied from, and which cohort.
• A one-way hashed form of your IP address and your browser user-agent string, used only to detect automated abuse. The hash cannot be reversed to recover your IP address.
• Whether you accepted advertising measurement on the notice bar, so we know whether we may report your application to Meta.

Your name, email address and answers are needed to consider an application; without them we cannot process it. Everything else on the form is optional, and advertising measurement is never a condition of applying.

If you join a cohort

• Your project name and description.
• Your progress against course milestones.
• Your weekly check-ins.
• Your AI usage allowance and consumption.

Automatically, in the mini app and on this site

• A session cookie so you stay signed in. It is strictly necessary for the app to function and contains no advertising or tracking identifiers.
• Standard server logs kept by our hosting providers.

Automatically, on lineappbuilders.com (our advertising landing site)

• An anonymous identifier for your browser (bom_journey_v1) and, if you arrived from an advertisement, the identifiers of that advertisement (bom_attr_v1: campaign, ad set and ad ids, and the fbclid Meta appends to the link).
• Events about how you use the page: which page and headline you saw, which button you pressed, whether you opened the application form, how far you got, and which field failed validation. Never what you typed. These go to our own server together with the hashed IP address and user-agent string described above.
• Only if you press Accept on the privacy notice bar: the Meta pixel, which sets Meta’s _fbp and _fbc cookies in your browser and reports page views, clicks on “Add us on LINE” and submitted applications to Meta Platforms so we can measure our advertising. If you choose Essential only, the pixel never loads and your application is not reported to Meta. You can change the choice at any time from the Privacy choices link in the page footer.

We do not track you across other websites ourselves. The Meta pixel loads only with your consent, only on lineappbuilders.com, and never on this site or in the mini app.

Browser storage we use

• bom_journey_v1 — the anonymous identifier above (lineappbuilders.com; until you clear your browser storage).
• bom_attr_v1 — the advertisement identifiers above (lineappbuilders.com; until cleared).
• bom_consent_v1 — your choice on the privacy notice bar (until cleared or changed).
• lineappbuilders_persona_v1 — which path you chose on the page, so it stays chosen (until cleared).
• bom_currency_v1 and bom.currency — whether you prefer prices in US$ or NT$ (until cleared).
• bom_apply_draft_v2 — the unsent draft of your application, so you can come back to it. Deleted when you submit.
• _fbp and _fbc — set by Meta, only after you accept (Meta keeps them for up to 90 days).

Why we use it

• To identify you so the app shows you your own application and your own course material.
• To assess your application and tell you its outcome.
• To run the programme — resources, progression, check-ins.
• To contact you about your application or your cohort.
• To keep the service secure and to prevent abuse.
• To see which advertisements and pages lead to applications, so we spend our advertising budget on what works. This uses the anonymous identifier and events, not your answers.
• With your consent, to report to Meta that an application was submitted, so Meta can show our advertisements to people more like those who apply.

We do not sell your personal data. We do not use it to train machine learning models. Your answers are never used for advertising. The only thing reported to Meta, and only if you accepted, is that an application happened, together with a one-way hashed form of your email address that Meta uses for matching.

Legal basis

Where the GDPR or a similar law applies, we rely on: performance of a contract (running the programme you applied to), your consent (which you give when you first open the mini app and LINE asks you to authorise it), and our legitimate interest in operating and securing the service.

In Taiwan, the Personal Data Protection Act applies. We collect your data for the specific purposes above after giving you the notice in the section below, as article 8 requires. When you submit an application after reading it, article 7 of the Act treats that as your consent. Advertising measurement is optional and happens only when you press Accept on the notice bar; declining it has no effect on your application.

Notice under Taiwan’s Personal Data Protection Act

For visitors and applicants in Taiwan, article 8 of the Act asks us to tell you:

• Who collects your data: Twenty Three Systems LLC, operating as BuildOn Marketplaces.
• For what purposes: running cohort admissions (reviewing applications, interviews, decisions), contacting you about your application and cohort, delivering the programme, keeping the service secure, and measuring our own advertising.
• What categories of data: identity and contact details (name, email address, LINE display name and user ID), your application answers, programme records if you join, technical data (hashed IP address, browser user-agent), and, on lineappbuilders.com, an anonymous browser identifier, advertisement identifiers and page events.
• For how long, where, by whom and how it is used: for the periods in the section How long we keep it; stored in Japan and processed in Taiwan, Japan and the United States; used by us and the providers in the section Who we share it with; by automated means online and by our staff.
• Your rights: at any time you may inquire about and review your data, request a copy, supplement or correct it, ask us to stop collecting, processing or using it, and ask us to delete it. Email privacy@buildonmarketplaces.com. We answer requests for access and copies within 15 days and requests for correction, deletion or a stop within 30 days, as the Act requires.
• If you do not provide it: without your name, email address and answers we cannot consider your application. Declining advertising measurement has no effect on anything.

Who we share it with

We share personal data only with service providers who process it on our behalf:

• Supabase — database and authentication. Data is stored in Tokyo, Japan (ap-northeast-1).
• Vercel — application hosting and server logs.
• Cloudflare — DNS, static hosting, and bot protection on our application forms.
• LY Corporation (LINE) — the platform the mini app runs on, and the channel through which we message you.
• Our customer-relationship and mailing tools, used to manage applications and to send you messages you have asked for. We only pass on the details you gave us when applying.
• Meta Platforms — only if you accepted on lineappbuilders.com: the pixel in your browser, and from our server one “Lead” event for your application carrying a one-way hashed form of your email address, your browser user-agent string and an event id, so Meta can match it and avoid double counting. Meta processes this in the United States under its own terms.
• PostHog — product analytics, if we enable it: receives the anonymous browser identifier and page events from our server, never your name, email address or answers.

We may also disclose data where we are legally required to, or to protect our rights or the safety of others.

International transfers

Your data is stored in Japan and may be processed in other countries where our providers operate, including the United States (Vercel, Cloudflare, Meta and PostHog). Where required, we rely on appropriate safeguards such as standard contractual clauses. Taiwan’s Personal Data Protection Act permits international transfer unless the competent authority restricts it; no such restriction applies to these transfers.

How long we keep it

• Application data, including applications made through our websites: up to 24 months after the decision, so we can consider you for later cohorts and answer questions about the outcome.
• Abuse-prevention data (hashed IP, user-agent): up to 12 months.
• Anonymous browser events and advertisement identifiers from lineappbuilders.com: up to 12 months.
• Your choice on the privacy notice bar: in your browser until you clear it or change it; on your application, for as long as the application.
• Participant records: up to 5 years after your cohort ends, for alumni support and our own records.
• If you block our Official Account we stop messaging you, but your application and course records remain until the periods above expire.

Your rights

You may ask us to:

• Give you a copy of the personal data we hold about you.
• Correct anything that is wrong.
• Delete your data, where we are not required to keep it.
• Restrict or object to how we use it.
• Withdraw consent, by blocking our Official Account and asking us to delete your data.
• Stop advertising measurement, by choosing Essential only under Privacy choices in the footer of lineappbuilders.com. That stops the pixel in your browser and any further reporting of your application to Meta.

Email privacy@buildonmarketplaces.com and we will respond within 30 days. You also have the right to complain to your local data protection authority.

Security

Data is encrypted in transit and at rest. Access to the database is restricted by row-level security so that one participant cannot read another’s records, and administrative access is limited to staff who need it.

No system is perfectly secure. If a breach affects your data and the law requires it, we will notify you and the relevant authority.

Children

The programme is for adults. We do not knowingly collect data from anyone under 18. If you believe a child has provided us data, contact us and we will delete it.

Changes

If we change this policy we will update the date above. Material changes will be announced in the mini app. The 8 September 2026 revision added the advertising landing site, the Meta pixel with its consent bar, the funnel events, and the Taiwan notice.