Open-The-File.com

Find how to open any file type

How to open .STPZ files on iOS

To open .STPZ files on iOS, iOS commonly won’t natively preview .stpz; try extracting it in the Files app (if offered) to get the .stp/.step inside, then transfer the .stp/.step to a desktop STEP-capable app for viewing/import.

Step-by-step instructions

  1. iOS commonly won’t natively preview .stpz; try extracting it in the Files app (if offered) to get the .stp/.step inside, then transfer the .stp/.step to a desktop STEP-capable app for viewing/import.

Common issues

The file won’t open because the app doesn’t recognize .stpz

Some tools support STEP but not the ZIP-packaged variant by extension, or they expect you to choose a specific “Compressed STEP” import format.

  1. In your CAD/translator, use Import (not double-click) and explicitly select “Compressed STEP (.stpz)” if available.
  2. If there’s no compressed STEP option, extract the .stpz as a ZIP and open the contained .stp/.step file instead.

Extraction works, but there is no .stp/.step file (or the contents look unexpected)

A valid .stpz should be ZIP-packaged STEP data; if the archive structure is unusual or the expected STEP file is missing, the file may be nonconforming or not actually a compressed STEP package.

  1. Re-download or re-export the file from the sender/source, ensuring they exported “compressed STEP (.stpz/.stepz)” rather than a different format.
  2. Compare the package to the industry recommended practices for STEP file compression and ask the sender to follow those conventions.

Importing .stpz overwrites files in the destination folder

Some import workflows may extract files into a working/destination directory and overwrite existing files with the same names.

  1. Import into a new, empty folder/project/workspace to prevent collisions.
  2. Before importing, back up the destination folder or use a unique extraction/import directory.

The .stpz opens, but the model is missing data or fails validation

Because .stpz is just compressed STEP Part 21 content, any limitations come from the underlying STEP data (AP choice, exporter settings, or translator support).

  1. Ask the sender to re-export the STEP with appropriate settings for your workflow (for example, a different STEP application protocol such as AP242 when applicable).
  2. If available, validate the STEP data in a dedicated conversion/validation workflow and try importing the uncompressed .stp/.step extracted from the archive.

Security note

.stpz is a ZIP container; treat it like any archive from an untrusted source because it can include unexpected extra files in addition to the STEP data.

Back to .STPZ extension page