| LA LIGA MEXICANA NINTENDO EDITION | Jerry Kalel Mtz. | J-League: Winning Goal | Sports | NES | G, T | Complete | 1.0 | 18 Jan 2021 |
| Jackal 2 | RayofJay | Jackal | Action > Shooter | NES | G, L, T, GP, O | Complete | 2.15 | 17 Feb 2020 |
| Jackal - War Safari | bogaabogaa | Jackal | Action > Shooter | NES | L | Improvement | 1.0 | 29 Feb 2020 |
| Jackal - Machine Gun Lock-off | Evgeny | Jackal | Action > Shooter | NES | GP | Improvement | 3f | 27 Jul 2020 |
| Jackie Chan Stage Select Hack | doomguard | Jackie Chan's Action Kung Fu | Action > Platformer | NES | O | Improvement | 1.0 | 01 Feb 2016 |
| Jackie Chan's Hulk Smash! | ALEX KO | Jackie Chan's Action Kung Fu | Action > Platformer | NES | G | Improvement | 1.0 | 11 Mar 2020 |
| Jeopardy: Battletoads Edition | Murugo | Jeopardy! 25th Anniversary Edition | Puzzle | NES | G, S, T | Complete | 1.1 | 30 Sep 2012 |
| Joe & Mac Improvement | the jabu | Joe & Mac | Action > Platformer | NES | G, GP | Improvement | 1.0 | 08 Nov 2015 |
| Joshua (Redesign) | Immutable | Joshua & the Battle of Jericho | Puzzle | NES | G, T | Improvement | 7.1 | 23 Mar 2018 |
| Joshua: the Restored Levels | Immutable | Joshua & the Battle of Jericho | Puzzle | NES | G, L, T, GP | Complete | 7.0 | 19 Aug 2018 |
| Journey to Silius Plus | alzen | Journey to Silius | Action > Platformer | NES | G, L, T | Complete | 1 | 09 Dec 2011 |
| Journey to Silius - Original Sprites | RichterSnipes | Journey to Silius | Action > Platformer | NES | G | Improvement | 1.0 | 22 Sep 2015 |
| The Terminator | pacnsacdave, 8-bit fan | Journey to Silius | Action > Platformer | NES | G, T, GP, O | Improvement | 3.0 | 12 Mar 2019 |
| Journey to Silius – Boss Run | Quest Games | Journey to Silius | Action > Platformer | NES | L, GP | Improvement | 1.3 | 25 Dec 2018 |
| Journey to Silius MMC5 Patch | Dracula X | Journey to Silius | Action > Platformer | NES | O | Improvement | 1.1 | 17 May 2020 |
| Journey to Silius Level 5 Music Replacement | NK358 | Journey to Silius | Action > Platformer | NES | S | Improvement | 1.01 | 08 Feb 2020 |
| When Mario Attacks! | Redrum | Joust | Action | NES | G | Improvement | 1.0 | 01 Aug 2009 |
| Joust (Arcade Hack) | Immutable | Joust | Action | NES | G, T, O | Improvement | 1.0 | 03 Oct 2015 |
| Kid Niki 3 MMC-3 Hack | MottZilla | Kaiketsu Yanchamaru 3: Taiketsu! Zouringen | Action > Platformer | NES | O | Improvement | 1.0 | 06 Aug 2008 |
| Ren Adventures | Roket | Kaiketsu Yanchamaru 3: Taiketsu! Zouringen | Action > Platformer | NES | G, O | Improvement | 1.0 | 03 May 2020 |
