CASE STUDY/02·OBSCURA · FOSSSHIPPED 2025 · v2.1.0 · MIT
“PII redaction that never leaves the client.”
★ FOSS · LOCAL-FIRSTAAL's open-source PII redaction tool for ChatGPT prompts. 100% local, 56+ entity types, zero bytes to the wire. Built in a Forge sprint, released under MIT. Proof that Forge ships FOSS clients adopt before paying for the SaaS.
BYTES LEAKED0
ENTITY TYPES56+
EXECUTION100% Local
LICENSEMIT
TIME TO RELEASE4 Weeks
02 · THE BRIEFSolve PII before ChatGPT does.
Every client worried about the same thing: teams already pasting customer data, contract clauses, and internal numbers into ChatGPT. Compliance had memos, legal had policies, nothing stopped it. Opening a separate tool was more friction than the perceived risk. Obscura redacts before the prompt leaves the browser, not after a quarterly audit catches it.
03 · SCOPEDetection engine✓ INCLUDED
Browser extension✓ INCLUDED
Entity library (56+)✓ INCLUDED
Public GitHub release◐ LIVE
04 · HOW IT SHIPPED
Four weeks. Open by week five.
01 · SCOPEWEEK 1
Pick the entity library.
NER baselines plus regex for what NER misses at scale (emails, IBANs, license plates, project codenames). Settled on 56 entity types covering 95% of what clients flagged as “do not send.” Local-first, non-negotiable.
02 · BUILDWEEKS 2–3
Browser-side, no network.
WASM detection model running entirely in-browser. Prompt intercepted, redacted, sent. Zero round-trips. An inline overlay shows what's protected. Built as an extension because an SDK clients had to integrate would have killed adoption.
03 · HARDENWEEK 4
Audit, document, ship under MIT.
Security pass on the manifest permissions. Removed every analytics call. README written for a security team to vet before install. Released to GitHub under MIT with a single-binary install script.
04 · COMPOUNDWEEK 5 → ONGOING
Open-source release, paid SaaS to follow.
Public on GitHub, adopted internally by three agency clients in the first month. The SaaS version (central policies, audit logs, fleet management) is the natural Forge follow-up: same engine, different distribution.
01 · SCOPEWEEK 1
Pick the entity library.
NER baselines plus regex for what NER misses at scale (emails, IBANs, license plates, project codenames). Settled on 56 entity types covering 95% of what clients flagged as “do not send.” Local-first, non-negotiable.
02 · BUILDWEEKS 2–3
Browser-side, no network.
WASM detection model running entirely in-browser. Prompt intercepted, redacted, sent. Zero round-trips. An inline overlay shows what's protected. Built as an extension because an SDK clients had to integrate would have killed adoption.
03 · HARDENWEEK 4
Audit, document, ship under MIT.
Security pass on the manifest permissions. Removed every analytics call. README written for a security team to vet before install. Released to GitHub under MIT with a single-binary install script.
04 · COMPOUNDWEEK 5 → ONGOING
Open-source release, paid SaaS to follow.
Public on GitHub, adopted internally by three agency clients in the first month. The SaaS version (central policies, audit logs, fleet management) is the natural Forge follow-up: same engine, different distribution.
CLIENT QUOTE“We needed our team to stop pasting customer data into ChatGPT without deploying yet another security tool. Obscura solved it where the problem happens: the browser, not a policy doc.”
FOSS
Engineering Lead
AGENCY CLIENT · EMEA
BUILT WITHBunWebAssemblyBrowser extension APIRegex + NERGitHub ReleasesMIT
05 · WANT A TOOL LIKE THIS?Brief a Forge build.
Forge ships custom SaaS for clients, and the FOSS that earns trust first. Two-sentence intake, 24-hour response.
TYPICAL BUILD4–12 weeks
OPEN SLOTS · Q32 of 4