A door access control system replaces keys with credentials you can manage. Instead of cutting a key for every employee and rekeying a lock every time someone leaves, you decide in software who can open which door and when — and you can change it, or see who went where, in seconds. For any business past a handful of employees, that's the difference between hoping the right people have keys and actually controlling and auditing your doors.
This guide covers what a door access control system is, how it works, the credential options, the big cloud-vs-on-premise decision, what it costs, and how to choose. Where it helps, we'll use Verkada's access control hardware — which Monarch designs and installs — as a concrete example.
What is a door access control system?
A door access control system is the combination of hardware and software that decides whether a given door unlocks for a given person. Every system, simple or enterprise, is built from the same four parts:
- A credential — what the person presents: a key card, a fob, or increasingly a phone.
- A reader — the device at the door that reads the credential.
- A controller — the brain (often in a closet) that checks the credential against the rules and tells the lock to release.
- The locking hardware — the electric strike, maglock, or smart lock that physically holds or releases the door.
Tying it together is the management software, where you set who can go where and when, add or revoke people, and review the log of every entry. That software is also where the biggest modern decision lives — whether it runs in the cloud or on a server in your building (covered below).
If you want to go deeper on the models of access control — discretionary, mandatory, role-based, and rule-based — we cover those in the 3 types of access control. This guide stays focused on choosing and buying a door system.
How door access control works
The sequence at the door takes a fraction of a second:
- A person presents their credential to the reader (taps a card, or holds up a phone).
- The reader passes the credential to the controller.
- The controller checks it against the access rules — is this credential valid, and is it allowed at this door, at this time?
- If yes, the controller signals the lock to release, the door opens, and the event is logged. If no, the door stays locked and that, too, is logged.
That logging is half the value. A door access control system doesn't just keep the wrong people out — it gives you a time-stamped record of every entry (and attempt), which is what turns "someone got in" into "we know exactly who and when."
Credential types: cards, fobs, and mobile
What people carry to open the door has evolved, and most systems support more than one type at once:
- Key cards and fobs. The familiar plastic card or keyfob. A card access control system is still the most common setup — cards are cheap and easy to issue, though they can be lost, shared, or cloned if you use older low-security card formats.
- Mobile credentials. The phone becomes the key, using Bluetooth or NFC. There's nothing extra to print or hand out, credentials are issued and revoked instantly from software, and a phone is harder to casually pass around than a card. Verkada's mobile option, Verkada Pass, works this way.
- PIN codes and biometrics. Keypads and fingerprint/face readers, often combined with a card for higher-security doors (two factors instead of one).
The reader you choose has to match the credentials you want to support. Modern access control card readers like Verkada's AD34 are multi-format — they read legacy and modern cards and mobile credentials — so you're not locked into one credential type or forced to replace every reader when you modernize.
Cloud-managed vs. on-premise access control
This is the decision that shapes everything else about owning the system.
Traditional on-premise. The access control software runs on a server (a PC or appliance) in your building. You — or an integrator you call — maintain that server, apply updates, and manage backups. Remote access means VPNs and IT involvement, and multiple sites usually mean multiple servers to keep in sync.
Cloud-managed. The controllers connect to the internet and you manage everything from a web browser or app — no on-site server to maintain, automatic updates, and every site in one place. This is the model Verkada uses with Command: you add a door, set the rules, issue credentials, and pull entry logs from anywhere, with the controllers continuing to enforce access even if the internet drops (more on that below).
| Consideration | Cloud-managed | On-premise |
|---|---|---|
| Server | None — runs in the cloud | A server/appliance you maintain on-site |
| Updates | Automatic | You apply them |
| Remote access | Built in, from any browser/app | Usually needs a VPN + IT |
| Multiple sites | One dashboard for all | Often a server per site to sync |
| Outage behavior | Controllers enforce access offline, then sync | Depends on local hardware |
| Best for | Most businesses, multi-site, lean IT | Orgs with strict on-prem-only policies |
For most businesses today — especially anyone with more than one location, or without dedicated on-site IT — cloud-managed is the simpler, more secure, and more scalable choice.
What to look for in a door access control system
When you're comparing systems, these are the factors that matter most:
- Cloud vs. on-premise management. The single biggest long-term decision — it dictates what you maintain and how you administer doors.
- Credential flexibility. Multi-format readers that support cards, fobs, and mobile, so you can modernize without ripping out hardware.
- Offline resilience. The controller should keep enforcing access and logging events even if it loses internet or power — your doors can't depend on a live connection.
- Scalability. Controllers that scale from one door to many, and software that handles multiple sites from a single view.
- Integration with video. Tying access events to camera footage (so an unlock is matched to a clip) turns two systems into one investigation tool.
- Wiring and power. PoE-powered controllers simplify installation by carrying power and data over one network cable, avoiding separate power runs to each closet.
How much does a door access control system cost?
Cost is one of the most-asked access control questions, and the honest answer is that it scales with how many doors you're securing, because most of the hardware is per-door. A door system's price is built from:
- The controller — priced by the number of doors it manages.
- A reader (or two) for each door.
- Locking hardware — electric strikes or maglocks, which vary widely.
- Credentials — cards, fobs, or mobile licenses.
- Software/licensing — per-door or per-site, and on cloud systems this replaces the cost of running an on-site server.
- Installation — wiring, mounting, and integrating with the door hardware.
For reference, Verkada's controllers are priced by door count: the AC12 one-door controller starts at $899, the AC42 four-door at $1,999, and the AC62 sixteen-door at $5,999, with multi-format AD34 readers from $349. Because the system is cloud-managed, there's no on-site access server to buy or maintain, and the controllers carry a 10-year warranty. A small office securing two or three doors looks very different on paper from a multi-building campus — which is exactly why it's worth scoping the door count before pricing.
Door access control with Verkada
The access control Monarch designs and installs runs on Verkada's hardware and Command software, with no on-site server. The controllers scale with your door count:
- AC12 — a one-door controller that powers a lock, two readers, and door accessories from a single PoE cable, with onboard storage and processing so it keeps working through a power or internet outage. From $899. See the AC12.
- AC42 — a four-door controller for larger entries and small buildings. From $1,999. See the AC42.
- AC62 — a sixteen-door controller for campuses and multi-entry facilities. From $5,999. See the AC62.
- AD34 — a multi-format card reader that supports legacy and modern cards plus Verkada Pass mobile credentials. From $349. See the AD34.
Credentials can be printed cards or the Verkada Pass mobile app, access rules and users are managed in Command from any device, and because access control and Verkada's cameras live on the same platform, you can tie an unlock event directly to the camera clip of the door — the kind of unified record that makes audits and investigations fast.
Who uses door access control — and where
Door access control earns its place anywhere keys have become a liability:
- Offices and multi-tenant buildings — manage employee and visitor access by floor, suite, and schedule, and revoke a departing employee instantly. See office and government security.
- Schools and campuses — control exterior doors, lock down quickly, and keep an auditable record of entry. See education and campus security.
- Healthcare — restrict pharmacies, records rooms, and patient areas to authorized staff. See healthcare security.
- Retail and multi-site businesses — standardize who can open stockrooms and back doors across every location from one dashboard. See retail security.
Frequently asked questions
How much does a door access control system cost?
It scales with the number of doors, since most of the hardware is per-door. Expect to budget for a controller (priced by door count), a reader or two per door, locking hardware, credentials, software/licensing, and installation. As a reference point, Verkada's controllers start at $899 for one door (AC12) and $1,999 for four (AC42), with readers from $349 — and because the system is cloud-managed, there's no on-site server cost.
What's the difference between a card and a mobile credential?
A card (or fob) is a physical credential you print and hand out; a mobile credential turns the user's phone into the key. Mobile credentials are issued and revoked instantly in software with nothing to print, and are harder to share casually. Multi-format readers support both, so you don't have to choose one forever.
Do I need an on-site server for access control?
Not with a cloud-managed system. Traditional on-premise access control runs on a server in your building that you maintain; cloud-managed systems like Verkada's are administered from a browser or app with no on-site server, automatic updates, and all your sites in one place.
Does access control keep working if the internet goes down?
On a well-designed system, yes. Verkada's controllers store their access rules and processing onboard, so they keep granting access to valid credentials and logging events during an internet or power outage, then sync back up when the connection returns.
Can I keep my existing doors and just add access control?
Usually, yes — access control is added to existing doors by fitting the right locking hardware (electric strike or maglock), a reader, and a controller. The best fit depends on the door and frame, which is exactly the kind of thing worth assessing on a walkthrough.
What are the different types of access control?
There are a few "types" people mean. By credential: card, fob, mobile, PIN, or biometric. By management: cloud-managed vs. on-premise. And by model — how permissions are structured (discretionary, mandatory, role-based, rule-based), which we cover in detail in the 3 types of access control. For most businesses, role-based access on a cloud-managed system is the practical default.
How many doors can one controller handle?
It depends on the controller. Verkada's range covers one door (AC12), four doors (AC42), and sixteen doors (AC62), and you mix and match them across a building — a one-door unit at a side entrance, a multi-door unit at the main lobby — all managed together in one dashboard.
Choosing the right door access control system
A door access control system turns keys you can't track into access you fully control and audit. The biggest decisions are how you'll manage it (cloud vs. on-premise), which credentials you'll support (cards, mobile, or both), and how many doors you're securing — and the last one drives most of the cost.
If you're planning or upgrading access control, that's what we do. Talk to a Monarch security expert and we'll scope the doors, the controllers, and the credentials around your building — and show you what managing every door from one dashboard, with no on-site server, looks like.