Privacy Policy

This policy describes objtostl.com, a static site that converts Wavefront OBJ meshes to STL in the browser. It is written to match the way the site is built. If a sentence here ever disagrees with the software, the software is what you should trust, and this page should be corrected.

The short version

Your OBJ is read on your device. A Web Worker on that same device parses it and builds an STL. The download is a local Blob. There is no account, no mesh database, and no request whose job is to receive your file. We do not sell mesh data, because we do not receive it.

What happens when you convert

1. You choose a .obj file, or you drop it on the page. The browser File API reads the bytes in memory.
2. The page checks the size (the hard stop is 40 MB) and the extension. Images and STEP files are rejected in the page. They are not sent anywhere for a second opinion.
3. A copy of the bytes is transferred to a Web Worker. The worker decodes the text, scales it, and writes STL with Three.js.
4. Triangle count and bounding box are shown from that result. The WebGL preview can show that mesh on the grid. The preview uses the same local triangles.
5. Download creates a Blob and a temporary object URL, then clicks a local link. The URL is revoked after the save starts.

Changing units, scale, up-axis, or ASCII versus binary runs that worker path again from the copy already in the tab. It does not re-upload the file.

What you can verify

Open developer tools, select the Network panel, and convert a file. You should not see fetch, XHR, or form posts that contain your OBJ or STL. The converter code does not call fetch or XMLHttpRequest with your mesh, and it does not build FormData from it. The worker is a script loaded from this site like any other static asset. Its messages stay inside the browser.

The sample cube

“Load 10-unit sample cube” downloads /samples/unit-cube-10.obj from this website. That file is ours. It is a 12-triangle cube used to show scale. It is not your model, and pressing the button does not upload anything.

Local events

The converter dispatches a browser event named objtostl:analytics for three moments: file chosen (file_drop), parse finished (parse_ok), and STL saved (download_stl). The detail object may include file size in bytes, triangle count, unit, up-axis, scale, and whether the STL is binary. It does not include the file name, the OBJ text, or the STL bytes. This launch does not attach a third-party analytics script, an ad script, or a tag that listens for those events and ships them off. If that changes, this page will say so before the script is added.

Cookies, accounts, and storage

The converter does not set cookies and does not create an account. It does not write your mesh to localStorage or IndexedDB. There is no login. A host or browser extension could still store its own data; that is outside this page’s scripts.

What the server can still see

The site is static HTML, CSS, JavaScript, and a few images. The first visit downloads those files. A host that serves them may keep ordinary request logs: IP address, user agent, URL, and time. Those logs are about fetching the page, not about processing a mesh. Your OBJ is not part of the URL and is not part of a conversion API, because that API does not exist. Query strings such as ?units=mm only select a dropdown. They are not a copy of the file. Do not put a model into the address bar; nothing in the tool asks you to.

Fonts, libraries, and third parties

Pages use the system font stack. They do not request a font from a third-party CDN. Three.js is bundled with the site, not loaded from a separate hosted build at conversion time. Links to Bambu Studio, UltiMaker Cura, and PrusaSlicer leave this site. Those vendors have their own policies. We do not send them your mesh.

Advertising

No advertising script, ad slot, or ads.txt file ships with this site. A folder may exist in the source tree as a reminder that ads are not wired. It is not loaded by any page.

Children

The tool does not ask for age or identity. It is a file converter, not a social product. Do not submit personal data inside an OBJ comment if you would not want that comment on a shared computer. We still do not receive the file.

Contact

The contact page shows [email protected]. A message to that address is a normal email from your own mail app. This site has no contact form and still does not receive mesh files. Do not attach an OBJ or an STL.

Changes

If the architecture changes — for example if a real analytics tag or an ad script is added — this page will be updated in the same release. The date at the top is the date of this text.

Languages

This policy is published in several languages. If a translation disagrees with the English text, the English text is the reference.