NFC (Near Field Communication)
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NFC, or Near Field Communication, is a short-range wireless technology that lets two devices exchange small amounts of data when they are held within a few centimeters of each other. It operates at 13.56 MHz and supports contactless payments, transit cards, tap-to-pair, and reading small tags. NFC is intentionally very short range, which makes tapping deliberate and secure but rules it out as a mesh or long-distance transport.
How it works
NFC works over the 13.56 MHz band at extremely short range, typically up to about four centimeters. It can operate in passive mode, where an unpowered tag draws energy from the reader’s field to respond, or in peer-to-peer mode, where two powered devices exchange data. Data rates are low, on the order of hundreds of kilobits per second, which is ample for identifiers, small records, and payment tokens.
The very short range is a design feature, not a limitation to overcome. Requiring devices to nearly touch makes a connection an explicit, intentional act and narrows the window for interception. This is why NFC underpins contactless payment and access-control systems, where deliberate proximity is part of the security model.
Why it matters
NFC is ubiquitous in phones and cards, powering tap-to-pay, transit, event tickets, and quick pairing that hands off to another radio such as Bluetooth. Its strengths are simplicity, low power, and the trust that comes from deliberate near-contact.
Those same properties define its limits. NFC moves only small payloads over a few centimeters and connects two devices at a time. It is not a networking transport: it cannot relay across many devices, cover a room, or carry large files. It is best understood as a tap-to-exchange mechanism, often used to bootstrap a richer connection.
How it relates to Offline Protocol
Offline Protocol operates at a completely different scale. Where NFC connects two devices at a few centimeters, Offline Protocol forms a multi-hop mesh, DORS, across BLE, WiFi Direct, and the internet, relaying up to 8 hops and moving messages and files up to 100MB with automatic failover. NFC is point-of-contact; the mesh is area coverage and range extension.
The two can be complementary. A quick NFC or QR tap is a natural way to bootstrap trust between two phones, for example exchanging Ed25519 OfflineID keys on first contact, after which the encrypted session and any relaying happen over the mesh. For that longer-range peer link, see WiFi Direct, and for range extension see multi-hop relay.
Frequently asked questions
What is NFC used for?
NFC is used for contactless payments, transit and access cards, event tickets, reading small tags, and tap-to-pair handoffs, all over a range of a few centimeters.
Why is NFC so short range?
Its very short range is deliberate. Requiring devices to nearly touch makes each connection an intentional act and reduces the chance of interception, which suits payment and access-control uses.
Can NFC form a mesh network?
No. NFC connects two devices at a few centimeters and moves only small payloads, so it cannot relay across many devices or cover an area. A phone mesh like Offline Protocol handles range and relaying over BLE and WiFi Direct.
