key fob system


If you’ve ever stayed in a hotel, chances are you’ve used a key card to get into your room. Key fobs are an equally popular door entry device for apartment residents and office workers. Key cards and fobs are an important component of electronic access control systems, replacing the traditional lock and key.

In this guide, we review how key card and fob entry systems work, as well as the most common types of key cards and key fobs. Finally, we cover the pros and cons of setting up a key fob system and provide possible alternatives.

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What are key card and key fob systems?

Key card and key fob systems are a form of electronic access control used to manage access in and out of buildings. Fobs and key cards are electronic devices that allow authorized tenants to unlock doors. They’re a popular keyless entry system for businesses, apartments, industrial facilities, and other types of buildings.

Key card systems require three components:

  • Access credentials. Access credentials are key cards and key fobs or badges, the small electronic devices that tenants use to gain access. Fobs and cards have a built-in chip or sensor that communicates with the access reader.
  • Access reader. When a tenant holds their key card or fob up to an access reader, the reader scans it to verify their identity. After the resident is verified, the access reader instructs the door to unlock.
  • Electric or magnetic door lock. Access control systems require electric or magnetic door locks. The door lock receives a signal from the access reader to unlock, allowing a resident to enter.


Cost of key fob entry system

Key fob entry systems cost between $1,200 and $2,500 per door. The total cost depends on the technology powering your key fob system and the number of entryways you want to secure. For a more specific estimate, it’s always best to get a quote.

However, remember that these are just the costs for initial installation. Don’t forget that a residential key fob entry system will require you to purchase a steady stream of fobs as residents lose theirs, ask for replacements, or move out. Replacing key fobs costs anywhere from $50 to $400 per fob when accounting for hardware and programming time.


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Types of key cards and fobs

Not all door and gate fob systems work the same. There are many types of key card and fob systems out there. Each one uses a different technology to deliver signals to the access reader. Below we share four popular types.

Four popular types of key cards and fobs are:

  1. Wiegand key cards
  2. Swipe key cards
  3. RFID key fobs and cards
  4. Proximity cards


1. Wiegand key cards

Wiegand key cards are one of the earliest types of electronic key cards. The Wiegand key card is named after inventor John R. Wiegand, who discovered a way to use magnetic polarization to encode binary data into specially made wires.

Wiegand readers emit a magnetic field. When a user swipes their Wiegand card through a reader, the magnetic field affects the wires built into the card. The reader detects these changes to the wiring to verify the user’s credentials.

While Wiegand magnetic cards began gaining popularity back in the 1970s, Wiegand technology still forms the foundation of much of today’s access control ecosystem.


2. Swipe key cards

Swipe key cards also use magnetic technology. A swipe card has a black bar, which is a strip that has been magnetized with a unique pattern. When you swipe the card through a reader, the reader opens the door if it detects the correct pattern. The technology used by swipe cards is actually very similar to how credit cards work!

Swipe cards differ from Wiegand cards because they are manufactured and encoded differently. In contrast to Wiegand cards, swipe key cards can be wiped and rewritten to interact with a different reader or lock.


3. RFID key fobs and cards

RFID key fobs and cards are named after their primary component: the RFID tag. These tags are built into the fob or card. RFID key cards use these tags to interact with card readers through radio waves.

Here’s what happens when a tenant places an RFID key fob next to a reader:

  • Signals from the access reader reach the RFID key fob. RFID card readers emit electromagnetic fields known as excite fields. The fob must be in the range of this field to unlock the door.
  • The key fob sends a signal back to the reader. When the RFID fob sends the correct credentials to the reader, the reader unlocks the door.

While most RFID access control systems consist of a standalone reader installed next to a door, you can also purchase RFID door locks. These locks have built-in RFID readers.


4. Proximity cards

A proximity card (such as NFC tags) requires the user to be in close proximity to the card reader. Like RFID key cards, proximity cards also use radio waves to communicate with proximity readers. However, proximity systems use a different radio frequency than RFID keys do.

There are two types of proximity card readers: active readers and passive readers.


Active vs. passive proximity readers

While active and passive proximity readers work similarly, there is one crucial difference.

Both types of cards require power to exchange signals with a card reader. However, active proximity cards come with their own batteries. In contrast, passive cards are powered by their proximity to the electrical field emitted by card readers.


key card system user


How do key fob systems work?

Key fob entry systems use wireless signals to allow cards and fobs to communicate with an access reader. If the key card provides the correct credentials, the access reader instructs the door to unlock.

Here’s how to use a key fob system:

  1. Present your credentials. First, present your credential to the access reader. Most readers are installed right next to the door. If you have a swipe card, swipe it through the reader. If you have a touchless RFID key fob, you simply hold it up close to the reader.
  2. Access reader verifies credentials. Depending on the system installed, there are different ways for an access reader to verify your credentials. For example, Wiegand key cards use a series of magnetized wires to store their credentials. Other types of cards, like proximity and RFID cards, transmit their credentials wirelessly via an electric field emitted by the access reader.
  3. Access reader unlocks the door. Finally, the access reader verifies your credentials and unlocks the door.


Should you get a key card or key fob access control system?

Now that you know how a key card entry system works, we can help you decide if fob access control is right for your building.


Benefits of fob entry systems

  • Intuitive for tenants. Just tapping a card or fob against a reader is much easier than fumbling around with a key.
  • More data for staff. Building staff can monitor which doors are opened, and see which resident opened that door.
  • Easy administration. If a resident loses a key card or fob, you can deactivate that card individually instead of replacing an entire lock.
  • Effective for elevators. If you need to control access to elevators in your building, a fob system is effective at preventing unauthorized visitors or tenants from accessing floors they’re not supposed to.


Limitations of key fob systems

  • Inconvenient for residents. While using cards and fobs might be easy, keeping track of such small items sure isn’t. Tenants may lose or forget their fobs.
  • Unreliable. Fobs and cards can be finicky, and swipe cards are particularly damage-prone. Interference from credit cards, cell phones, and ever-present magnets can damage swipe cards. And when that happens, your renter is stuck with a useless piece of plastic.
  • Expensive to manage. When residents lose key cards, they aren’t the only ones affected. Property staff must replace residents’ lost key cards and fobs and ensure those residents get their new fobs in a timely fashion. Those costs add up.
  • Insecure. Believe it or not, key card systems can easily be bypassed (there are actually keycard duplicators on sale for less than $20). Additionally, there’s always the possibility of a resident losing a key card that somebody else uses before your staff can revoke access.
  • No guest access. Even the best key cards and fobs need to be near an access reader to open doors. With a fob or card system, there’s no way for residents to remotely grant access to guests.


keypad access control smartphone


Alternatives to key card and fob entry systems

While key cards and fobs are more convenient than traditional locks and keys, using key fobs for apartment buildings and offices isn’t the best solution. Other systems offer that same convenience without any of the downsides.

Consider an access control system that residents can use with their smartphones instead of fobs. Mobile access control systems maintain building security while offering unbeatable convenience for staff and tenants. Owners and managers avoid wasting time and money purchasing and programming fobs. And tenants never have to worry about losing or forgetting their fobs or keycards — they can always gain access from a mobile app on their smartphones.

Invest in a smartphone-based access control solution with:

  1. Keypads for interior access
  2. Video intercom for front door access


1. Keypads for interior access

Fob systems are most often used to manage access to amenities like gyms and rooftops. But that means tenants have to carry fobs or cards everywhere they go. So, replace the physical keys with a keypad at each door.

The best keypads offer two entry methods:

  1. PIN code: Tenants can enter their unique PIN or use a Virtual Key to open the door.
  2. Mobile app entry: Tenants can swipe to open the door from the system’s mobile app on their smartphones.


2. Video intercom for front door access

Key fob systems only allow access for tenants — but what about guests? Integrating your access control system with an IP video intercom gives visitors and delivery carriers a way to access the building.

The best video intercoms have features like virtual keys for guests and delivery PINs for couriers. You should also choose an intercom that provides an audit trail of all door releases for added security.



Key cards and fobs offer significant advantages over traditional locks and metal keys. However, fob access control systems are cumbersome, inconvenient, and expensive to maintain. All types of key fob systems — Wiegand, swipe, RFID, and proximity — share one big drawback: forcing users to carry around pieces of easily lost hardware.

Today, mobile access control systems render the key card and the key fob obsolete. Residents with smartphones in their pockets can open doors, let in guests, and accept deliveries, ensuring a secure and convenient access experience.


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Ferdison Cayetano

I’m a proptech enthusiast from New Jersey who’s looking forward to the innovations that will revolutionize real estate.

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