Free while we build it with you.
We're onboarding a small group of firms to shape zspan. Beta access is free, and founding firms keep preferred pricing at launch.
Full access during the beta for invited engineers and firms.
- Web app, plus Windows and Mac desktop apps
- AI assistant and Python included
- Direct line to the team; your feedback sets priorities
On the roadmap
- ACI 318 Chapter 18 special walls and boundary elements
- Cloud projects, sharing and team history
- Reinforcement detailing and drawings, and a Revit round-trip
- Signed Mac and Linux desktop builds
- Published side-by-side comparisons with ETABS on real buildings
Already shipped: SAFE-style slab design (strips, punching shear with drop panels, studs and openings, cracked long-term deflection), mats and footings on soil, and SAFE model import.
Questions engineers ask.
Can I open my existing ETABS models?
Yes. In the browser, open an .e2k text export (ETABS: File → Export → ETABS .e2k Text File). In the Windows app you can also open .EDB files directly: zspan uses your installed ETABS to convert them. Frames, walls, slabs, materials, library sections, loads, auto lateral loads, cases, spectra and combinations are imported, and anything not yet supported is listed clearly. The Windows app can also run ETABS on the same model and compare results side by side.
Which design codes are supported?
Loads: NBC 2020 and ASCE 7-16 (seismic, wind, combinations). Member design: CSA A23.3-19 concrete columns, walls and beams (Clause 21 ductile walls in progress), CSA S16 steel, AISC 360-16 steel and ACI 318-19 concrete frames, each with step-by-step calculation sheets.
Which units can I use?
Metric (kN, m, mm, MPa) and U.S. customary (kip-ft or kip-in). Imported ETABS models keep their units, and exports use them too.
Where does my model go?
Analysis runs on your own computer, in the browser or the desktop app. If you use the AI assistant, the parts of the model and results it needs to answer are sent to the AI model for that request (the hosted beta uses OpenAI models through OpenRouter). You can turn the assistant off for any project (Assistant → Turn Off for This Project); the setting is saved with the model, and nothing from that project is sent anywhere. See the privacy notice.
How do I know the results are right?
CSI's published ETABS and SAFE verification problems and our unit tests run on every release, and a deploy stops if any of them fails. Frames and shells were also compared against OpenSees and closed-form solutions (see Verification). Every analysis also produces a hand-check report you can review and keep with your calculations.
Does it replace ETABS?
zspan covers linear analysis and design of frame and wall buildings, and adds the assistant, scripting, calculation sheets and automatic checking. We are comparing it with ETABS on real projects with beta firms and will publish those results with their permission. Nonlinear and time-history analysis, some design modules and detailing are on the roadmap. If you need to stay on ETABS, zspan works with your ETABS models: open them to run the independent checks report or a second analysis, and export changes back. ETABS is a trademark of Computers and Structures, Inc.; zspan is independent.
Do I need to install anything? Windows, Mac, Linux?
No install is needed: the web version runs in Chrome, Edge, Safari or Firefox on any system, and the analysis runs on your own computer (the optional assistant sends the model data a request needs to the AI provider). Windows and Mac desktop apps are available; the Mac build is not yet signed, and Linux is planned.