The problem with 3D file sharing
Every day, designers publish STL, OBJ and STEP files to sharing sites — but with no provable timestamp. If someone copies your work later and claims they designed it first, you have no cryptographic evidence to the contrary. Copyright claims become "he said, she said" disputes.
Immutable provenance, for everyone
When you upload to ModelDirectory.org, we compute a SHA-256 fingerprint of your file and write it to the Polygon blockchain. That on-chain record is permanent and tamper-proof. Anyone can verify the hash at any time — no account required, no trust in us needed.
Open directory, not a walled garden
Our model listings are free to upload and free to browse. We believe the 3D printing and design community deserves a neutral, permanent index — not another platform that can delete your work or change monetisation rules mid-stream.
Verifiable without an account
Our public verification page lets anyone drop in a SHA-256 hash or upload any file to check whether it was registered with us and when. Verification works forever — even if the original uploader deletes their account.
Two layers of provenance
Every model gets a free off-chain certificate (instant). Optional blockchain anchoring adds an on-chain record that outlasts our own servers.
Off-chain Certificate
An Ed25519-signed certificate issued the moment your file is accepted. Contains your SHA-256 hash, upload timestamp and creator name. Verifiable with our public key. Free for all uploads.
Polygon Timestamp
Your file's SHA-256 hash is written to a smart contract on Polygon. The transaction is permanent and publicly readable on Polygonscan. Provides cryptographic proof that your file existed at a specific date and time.
Notarised Certificate
A legally formatted provenance certificate combining the off-chain and on-chain records, suitable for copyright dispute evidence. Planned for a future release.
Supported file formats
We accept all major 3D file formats used by designers, engineers and makers.
The team behind ModelDirectory.org
Christopher Howard
Founder & Senior Engineer
Retired civil engineer with 25+ years in commercial construction — bridges, high-rises, infrastructure. Author of 3D Printing Artificial Coral Reefs (Amazon, 2024), exploring how 3D printed concrete can restore marine ecosystems. Former PADI dive instructor. Currently lives on a sailboat, splitting time between the Mediterranean and Caribbean.
Josh Green
Lead Developer
Web developer and 3D printing maker. Built ModelDirectory.org from the ground up — the search engine, blockchain provenance system, cross-platform crawler, and AI model analysis pipeline. Runs a Bambu Lab P1S and is active in the 3D printing community. Writes about web development and 3D workflows.
Built for makers, by makers
ModelDirectory.org is live, growing, and free to use. Upload your first model today.
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