The problem with 3D file sharing
Designers post STL, OBJ and STEP files every day, and none of it carries a provable timestamp. So when someone copies your work and claims they made it first, you can't prove otherwise. The whole thing turns into "he said, she said."
Provenance for everyone
Upload a file and we compute its SHA-256 fingerprint, then write that to the Polygon blockchain, and to Bitcoin through OpenTimestamps for the most durable record. Permanent and tamper-proof. Our registry contract is public on Polygonscan, so nobody has to take our word for anything. Most of the catalog also carries a geometric shape fingerprint that recognizes the same object even after a re-export or re-mesh; we use it to catch duplicates across the catalog. The whole system is explained on the provenance page.
Open directory, not a walled garden
Listings are free to upload and free to browse. The 3D printing and design community deserves a neutral, permanent index. Not another platform that deletes your work or rewrites the monetisation rules on you mid-stream.
Verifiable without an account
Our public verification page lets anyone drop in a SHA-256 hash, or upload a file, to check whether it was registered with us and when. It keeps working even if the original uploader deletes their account.
Two layers of provenance
Every model gets a free off-chain certificate the moment you upload. Want more? Anchor it to the blockchain and the record 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 engineer with years of experience in construction. 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 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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