Do I need to install .NET 8?
No. The installer bundles everything needed to run the app.
System
Installation and trial guide
How to download, install and sign in for the first time on MK3 NFS-e Desktop with the free 15-day trial.
Download the installer
Get Mk3NfseDesktop-win-Setup.exe for Windows. The 15-day trial uses the same file.
Default login (first access)
Login
adminPassword
Admin@1231. What is the trial version?
- The trial uses the same installer as the full product — there is no separate trial file.
- 15 days of use starting from the first successful login.
- Starter plan limits: 1 operator and up to 2 service providers.
- Invoicing, records and other features are available during the period.
- After 15 days, the app asks for a Starter or Business license from MK3.
2. System requirements
| Item | Requirement |
|---|---|
| Operating system | Windows 10 or 11 (64-bit) |
| .NET | Not required — the runtime is bundled in the installer |
| Internet | Required for live issuing and automatic updates |
| A1 digital certificate | Required for production (import later in Settings) |
3. Download
If download is unavailable, email contato@mk3.tech to request the installer.
- Use the download button at the top of this manual or on mk3.tech/en/systems/nfse.
- Click “Download 15-day trial” (the full installer uses the same file).
- Wait for Mk3NfseDesktop-win-Setup.exe to download.
4. Install
After the first install, the app checks for updates on startup and updates itself — no manual download needed.
- Find Mk3NfseDesktop-win-Setup.exe in Downloads.
- Double-click to start installation.
- If Windows SmartScreen appears, click “More info” → “Run anyway”.
- Follow the wizard to finish.
- Open the app from the Start menu or the option at the end of setup.
5. First sign-in
On first run, the app creates an administrator user. Use the default credentials below, then change the password.
First login steps
- Open MK3 NFS-e Desktop.
- Enter login admin and password Admin@123.
- Click Sign in.
- In “Change initial password”, enter a new password (at least 6 characters) and confirm.
- Click Save password.
- On the License screen, review the trial message and click Continue.
- The main app opens.
6. Trial period (15 days)
Track remaining days on the License screen or in Settings (administrator).
| Item | Detail |
|---|---|
| Starts | On first successful login |
| Duration | 15 calendar days |
| Equivalent plan | Starter (1 operator, up to 2 providers) |
| Paid license | Not required during the trial |
When the trial ends
- Contact MK3: contato@mk3.tech
- Choose Starter or Business.
- Receive your license key.
- In the app: Settings → paste the key → Activate license.
7. Next steps after install
- Settings (admin): provider data, environment and A1 certificate import.
- Clients: register customers (tax ID).
- Services: review the national service catalog.
- Issue invoice: pick provider, client, service, amount and issue NFS-e.
8. FAQ
Does the trial use a different installer?
No. Both buttons on this site download the same Setup file.
I forgot my password after changing the initial one
Ask your system administrator or MK3 for a reset. Default Admin@123 only works until you change it on first login.
Can I use it on more than one PC?
Each install has its own local SQLite database. To share data across machines you need centralized PostgreSQL — contact MK3.
Does Windows clock affect the trial?
Yes. Rolling back system date/time to “gain” days can end the trial immediately. Keep the clock accurate and synced.
Where is my data stored?
By default in %LocalAppData%\Mk3Nfse\ (type that path in File Explorer’s address bar).
9. Support
- MK3 Soluções Ltda
- Website: mk3.tech/en
- Email: contato@mk3.tech
- Product: mk3.tech/en/systems/nfse
Last revised: September 2026 — MK3 NFS-e Desktop