Field note /
Filing Harbor keeps tax draft data in the browser by design
Filing Harbor's public demo keeps tax draft data and imported documents in browser memory. The server receives only the limited inputs for one calculation.
How the finding changed
Belief
A public tax demo could protect privacy mainly by turning off ordinary server storage.
Evidence
In the supported workflow, the draft, household names and addresses, dependents, correction history and imported documents stay in browser memory for the life of the page. Durable tax-draft API routes are unavailable in the public demo.
Contradiction
A promise in the interface not to save data would leave it unclear who owns the data if the browser used durable storage or the server exposed storage routes.
Correction
Make the design enforce it. Tax records never go into browser storage. The server accepts only narrow request formats. Data clears when the page ends, and late responses are ignored.
Current claim boundary
A real-browser synthetic calculation showed zero durable API requests, zero tax-draft storage keys and cleared wages after reload. The server still processes limited calculation and eligibility inputs for each request. The demo is not for filing. Scanned-document reading and fully offline use are not claimed.
Evidence
- Browser-owned demo implementation (private repository)Private