E-Reader

The e-Reader is an add-on device for the Game Boy Advance released in 2001 that can read dot codes on special cards and interpret them into data. Depending on the card, the data may contain either information or some type of minigame. Several Nintendo Entertainment System games were also made available on special packs of cards, but the 2-player modes have been removed. It took a total of nine or ten dot codes (two per card) to store the data of an NES game.

Additionally, the Nintendo DS, while compatible with Game Boy Advance games, was not designed to work with the e-Reader, but it can be modified to fit in. It works on a Nintendo DS or DS Lite if the player were to open up the e-Reader and remove the Game Boy Advance Link Cable extension wires. The device was never released in Europe, with Nintendo saying "the market potential wasn’t great enough". As a result, e-Reader functionality was absent in the European versions of the respective games. The device is compatible with the Game Boy Advance SP; however, it does not mount evenly.

There are two versions of the e-Reader. The original 2001 version, which never left Japan, had no linking capabilities, and thus was unable to be used for games such as Super Mario Advance 4: Super Mario Bros. 3. It also could not store games due to memory limitations. In 2002, Nintendo added linking capabilities, the ability to store games, and emulate NES titles when it released this new version in North America. This updated version was released as the "Card e-Reader +" in Japan in 2003, but with an attachable plastic cover to protect the link socket and the screen when mounted to the newly released Game Boy Advance SP. The Australian release also came with the plastic cover when it was released a few months later. Japanese e-Readers, regardless of the version, cannot read foreign e-Reader cards. The same is true for foreign e-Readers and Japanese cards. Australian and North American e-Readers are compatible with each other's cards.

The e-Reader was packaged with a classic NES game (either Donkey Kong Jr.-e or Pinball-e) and a "sampler pack" containing an Animal Crossing card, three Pokémon cards (Machop, Machoke, and Machamp) that allowed a minigame to be played, and a Game & Watch card that contained Manhole. Australian copies also included a Hockey Card-e game (released as Air Hockey-e in North America).

Four series of e-Reader cards were released for use with Animal Crossing. Some cards featured Mario-themed designs that could be uploaded into the game. One card even rewarded the player with a copy of Mario Bros. to place in their home.

In 2003, Nintendo released Mario Party-e, a portable board game which included numerous e-Reader cards, some of which contained minigames. However, the e-Reader was not mandatory in order to play the main game.

Later that year, Super Mario Advance 4: Super Mario Bros. 3 was released. By linking a Game Boy Advance with the game to a second Game Boy Advance with an e-Reader, a player could use three special types of cards. In 2004, Nintendo discontinued the e-Reader outside of Japan due to low sales. However, it was supported in Japan until the end of the Game Boy Advance's lifespan. As a result, many cards, particularly the new Super Mario Advance 4: Super Mario Bros. 3 levels, a planned series of Game & Watch releases, and a set of bonus levels for Mario vs. Donkey Kong, were never seen elsewhere. The unreleased Super Mario Advance 4 levels were eventually made available internationally when the game was released on the Wii U Virtual Console, which has all of World-e unlocked from the start. In 2023, these levels would also be made available again on Game Boy Advance - Nintendo Switch Online.
 * Power-Up Cards: A player could scan in items to add to their inventory. There was no limit to this option. There were also special switches that triggered new options in the game.
 * Demo Cards: Upon scanning a Demo Card, the player was treated to recording of how to either uncover a secret in a level, or see a single-level speedrun.
 * Level Cards: Probably the most desired, scanning these would add brand new levels into the game.

The Mario Kart: Super Circuit website suggested that e-Reader compatibility might have been planned for this game.

Compatible games

 * Mario Party-e
 * Super Mario Advance 4: Super Mario Bros. 3 (cards)
 * Mario vs. Donkey Kong (Japan only) (cards)