Thank-you cards, e-cards and "teacher appreciation week" posts already exist, and alumni sites list who went to which school. But every thank-you is a private, one-off message that vanishes. Thank-You Tree turns each letter into a node in a shared map: when other people thank the same teacher, coach or mentor, the trees connect, so a chemistry teacher in Lagos can finally see that she shaped 214 lives across 31 years. Nobody has built the public, consented graph of who shaped whom.
Source: only what users write: the person's name, their role, the place (school, club, town) and years, plus the story. There is no scraping and no public dataset of teachers.
Matching: a person node is created from name plus place plus role. New entries are matched with fuzzy name matching ("Mrs F. Adeyemi" and "Folake Adeyemi") within the same school, using a school list drawn from open registries where they exist (for example the UK's Get Information About Schools register or national education ministry lists), and user-added places elsewhere. Two strangers' entries only merge when both users consent and the years overlap plausibly.
Limits and gaps: common names in big schools collide, so uncertain matches are shown as "maybe the same person?" for users to confirm. Many teachers have died or cannot be reached; their page can be kept by family or the school. Some countries have no open school register, so places are user-created and deduplicated by moderators.
Fallback: without any match, the tree still works as a private gratitude journal and letter writer.
Make visible the invisible work of the people who shape us. Every teacher, coach and aunt deserves to know, while they are still here, what they started.
Near zero: a style sheet once (about $0.001), a letter draft (about $0.004 with Claude Haiku or Gemini Flash, $0.02 with a frontier model), matching checks a fraction of a cent. Printing and posting a physical letter is passed through at cost (about $2).
Free: unlimited people, letters and the network. Paid: printed letters and a "book of thanks" for retiring teachers that schools and classes chip in for (about $25), plus a school plan for alumni offices.
Every letter that reaches a teacher invites them to claim their page, and teachers share "214 people thanked me" with pride, which reaches the other 3,000 students who never wrote. Alumni groups pass the link around before reunions and retirements. Each month the gratitude calendar suggests one more person, timed to a birthday or retirement, so the tree keeps growing and replies keep arriving in your inbox.