Single-family residential ≤ 300 m² (basement included) is free forever. No credit card, no time limit. Subscriptions only kick in when you outgrow the residential cap or need team features.
Residential dwelling ≤ 300 m² (basement included). Save unlimited residential projects, export reports, generate SLD.
Independent engineers + small contracting offices. All occupancies, any size, full feature set.
Engineering firms with up to 10 seats. Team workflow, comments, status approval, role permissions.
Large firms, utilities, and AHJs. SSO, white-label, custom rule packs, on-prem export connector.
| Feature | Free | Pro | Professional | Enterprise |
|---|---|---|---|---|
| Project size limit | ≤ 300 m² residential | Unlimited | Unlimited | Unlimited |
| Occupancy types | Residential dwelling | All | All | All |
| Live calculation engine | ✓ | ✓ | ✓ | ✓ |
| Rule trace per number | ✓ | ✓ | ✓ | ✓ |
| Single-line diagram (SVG) | ✓ | ✓ | ✓ | ✓ |
| Conduit fill | ✓ | ✓ | ✓ | ✓ |
| Panel schedule + leg balance | ✓ | ✓ | ✓ | ✓ |
| PDF report export | Watermarked | Branded | Branded | White-label |
| CSV / Excel import | — | ✓ | ✓ | ✓ |
| Equipment library | View only | Full + custom | Full + custom | Full + custom |
| Templates | Built-in 4 | + custom | + shared team | + firm-wide |
| Branching + version history | ✓ | ✓ | ✓ | ✓ |
| Immutable change log | ✓ | ✓ | ✓ | ✓ |
| Per-element comments | — | — | ✓ | ✓ |
| Status workflow (review/stamp) | — | — | ✓ | ✓ |
| Team seats | 1 | 1 | Up to 10 | Unlimited |
| Polling-based collaboration | — | — | ✓ | + realtime |
| SSO (SAML / OIDC) | — | — | — | ✓ |
| Custom rule packs | — | — | — | ✓ |
| SLA | — | Best effort | Best effort | 99.9 % |
If your project occupancy is "Residential dwelling" (single-family, duplex, townhouse) and the floor area is ≤ 300 m² (basement included in the count), you can save unlimited projects, export branded PDF reports, generate single-line diagrams as SVG/PDF, run the full rule trace, and use all 26 engineering warnings — at $0, no time limit, no credit card. The same engine that paying customers use.
Once you set the floor area above 300 m², the engine emits a FREE_TIER_GATE notice and the platform asks for a Pro subscription before saving or exporting. Calculations still run live so you can preview, but persistence + export are gated.
Multifamily projects (3+ units) trigger NEC 220.84 / CEC 8-200(b) demand factors and per-unit metering decisions that need professional engineering judgment and longer audit trails. Putting them in the paid tier covers the support cost and the licensed-engineer review the projects deserve.
Yes — Pro and above. Paste your Excel rows directly (CSV or TSV) into the workflow's "Import from CSV / Excel" dialog. The parser tells you exactly which rows had problems before you commit, and the imported loads inherit your project's default panel.
Yes — same project payload, switching the standard between NEC 2023 and CEC 2024 fires different rules and produces different demand numbers. Proven by 16 spec assertions in the open-source rule-pack test suite.
The PDF is permit-shaped (cover with project photo, sections 1-9 mirror of the engineering report template, engineer-of-record signature block, full disclaimer appendix) — but it is reference material until a licensed P.E./P.Eng signs and seals it. EEP does not certify designs.
Yes. Every save creates a versioned snapshot in the database. The change log is append-only and immutable — no API can mutate or delete a logged action. You can restore any older version, branch into a new project, or export the full history at any time.
On Professional and above. The platform uses optimistic concurrency control — if two engineers save against the same version, the second save gets a 409 conflict with the other engineer's email and timestamp, so neither overwrites the other. Polling shows a collab indicator when teammates are saving.
Cancel anytime — no contract on Pro / Professional. Your projects remain accessible for 90 days after cancellation in read-only mode so you can export them. Free residential projects under 300 m² remain accessible forever regardless of subscription state.