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STP converter

Files named .stp are STEP models wearing the three-letter extension that DOS-era 8.3 filename limits made necessary; there is no format difference between .stp and .step. Inside is an ISO 10303 product model — precise solid geometry written as plain text for exchange between CAD systems.

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Drop STP files here

Batch files can each use a different output. Nothing uploads for local conversions.

Working inputs include camera RAW, browser-local audio/video, PDF, CBZ/CBR comics, office documents, ebooks, markup, 3D models, structured text, images, and archives.

Where STP comes from

When the STEP standard's Part 21 encoding was published in 1994, much of the software world still ran on operating systems that truncated extensions to three characters, so exporters settled on .stp. The habit outlived its cause: decades later many CAD packages still write .stp by default even though .step is equally valid.

How STP works

  • Byte-for-byte the same syntax as .step, so renaming between the two extensions changes nothing about how any parser treats the file.
  • Represents exact boundary-representation solids and assemblies rather than approximated meshes.
  • The governing application protocol — AP203, AP214, or AP242 — is declared in the file header, not by the extension.
  • Encoded as ASCII text, so the file can be sanity-checked in any editor.

When to use STP

  • Sending exact solids to machine shops and suppliers that request the .stp spelling
  • Importing vendor part libraries, which ship overwhelmingly with the short extension
  • Feeding legacy PLM and CAM systems that filter uploads on three-letter extensions

Strengths and limitations

Strengths

  • Identical fidelity to .step in every respect
  • Recognized by effectively all engineering software
  • Safe to rename when a picky tool filters on one spelling

Limitations

  • The dual naming causes confusion and duplicate entries in format lists
  • Inherits STEP's traits of large text files and lost parametric history

Compatibility

Any application that opens .step opens .stp — the import filters in SolidWorks, Fusion 360, FreeCAD, and their peers list both spellings together. If a strict tool accepts only one variant, renaming the file suffices, because the content is indistinguishable.

Identical to the longer spelling: header fields for author, organization, and originating system, plus named product structure inside the data section.

Convert STP to another format