Kindle Font Hack for all 2.x, 3.x and 4.x Kindles
Many thanks to porkupan (jailbreak hack) clarknova (revised jailbreak hack) and NiLuJe (another revised jailbreak and font hack).
Note: Amazon does not support 3rd party hacks and may void your warranty should anything go wrong. Exercise caution and use at your own risk. Only the user will be responsible for the results (good or bad).
Please visit NiLuJe's Fonts & ScreenSavers hacks for Kindles thread on MobileRead. This is the jailbreak and font hack I will be describing.
WARNING: Use at your own risk! This is an UNOFFICIAL update to allow custom Kindle Fonts. This file is NOT from Amazon.com and any harm it causes your Kindle will be your own fault.
Software: Fonts & ScreenSavers hacks for Kindles Note: the software for this hack has been updated several times since the images in this guide were created. The process for installation is the same even with the updated files. The font of your choice: Droid_Sans Diavlo Fertigo Pro Fontin Delicious Museo Museo Slab Museo Slab BIG Museo Slab BIG 125% Museo Slab BIG 150%
Forum user NogDog made a helpful webpage listing some of these fonts with a sample screenshot: check it out here!.
 Which Kindle Do You Have
And for other devices, check the Menu > Settings page.
Kindle DX Graphite: Serial no. prefix B009
Kindle 3 3G US: Serial no. prefix B006
Kindle 3 WiFi: Serial no. prefix B008
Kindle 3 3G UK: Serial no. prefix B00A
Kindle 4: Serial no. prefix B00E & B023
NOTE to non-US users: UK doesn't necessarily mean Europe, you may very well end up with a B006 model, depending on your country.
 How to install the Jailbreak Hack
Note for Kindle 4 Users:
Please skip this section and refer to the Wiki instead.
1) Download and unzip the kindle-jailbreak-0.11.N.zip file.
Note for Kindle 3.0.x, 3.1.x & 3.2 Users:
Please use the file corresponding to your kindle model suffixed by -3.0-to-3.2, the other one won't work on these older FW versions, while this one won't work on newer FW versions. Check your Settings page if you're unsure of what FW your Kindle is running.
"update_jailbreak_0.11.N_k2_install.bin" - Kindle 2 US "update_jailbreak_0.11.N_k2i_install.bin" - Kindle 2 International "update_jailbreak_0.11.N_dx_install.bin" - Kindle DX US "update_jailbreak_0.11.N_dxi_install.bin" - Kindle DX International "update_jailbreak_0.11.N_dxg_install.bin" - Kindle DX Graphite "update_jailbreak_0.11.N_k3g_install.bin" - Kindle 3 3G US "update_jailbreak_0.11.N_k3w_install.bin" - Kindle 3 WiFi "update_jailbreak_0.11.N_k3gb_install.bin" - Kindle 3 3G UK "update_jailbreak_0.11.N_k3g-3.0-to-3.2_install.bin" - Kindle 3 3G US (Only if running FW <= 3.2.0) "update_jailbreak_0.11.N_k3w-3.0-to-3.2_install.bin" - Kindle 3 WiFi (Only if running FW <= 3.2.0) "update_jailbreak_0.11.N_k3gb-3.0-to-3.2_install.bin" - Kindle 3 3G UK (Only if running FW <= 3.2.0)
2) Attach your Kindle to a computer using the USB cable. Copy the appropriate jailbreak bin file to the root of your Kindle. Below are images for Kindle 2 International and Kindle 3 3G + WiFi. (Note: If you've previously installed the jailbreak from the Screen Saver Hack, there is no need to install it again).
3) Safely eject your Kindle from your computer. To update your Kindle with jailbreak bin from the home page, click Menu > Settings > Menu > Update Your Kindle. If "Update Your Kindle" is grayed out, you either did not put the bin file in the root folder or used the wrong file for your Kindle.
On FW 2.x only, the jailbreak update process will FAIL (with a U006 error in the lower left corner of the screen) but that's okay, it's supposed to. :)
To remove the jailbreak (if you somehow want to get rid of it... There's no practical reason to do this though ;)) use the same process described substituting the appropriate "uninstall" bin file.
 How to install the Font Hack
1) Download and unpack the kindle-fonts-5.7.N-k2.rar file (if you have a K2, K2I, DX, DXI or DXG), the kindle-fonts-5.7.N-k3.rar file (if you have a K3 3G, K3 WiFi, K3 3G UK) or the kindle-fonts-5.7.N-k4.rar file (if you have a Silver or Black K4).
2) Attach your Kindle to a computer using the USB cable.
3) Copy the appropriate fonts bin file to the root of your Kindle along with the "linkfonts" folder found inside the "src" folder.
"update_fonts_5.7.N_k2_install.bin" - K2 US "update_fonts_5.7.N_k2i_install.bin" - K2 International "update_fonts_5.7.N_dx_install.bin" - Kindle DX US "update_fonts_5.7.N_dxi_install.bin" - Kindle DX International "update_fonts_5.7.N_dxg_install.bin" - Kindle DX Graphite "update_fonts_5.7.N_k3g_install.bin" - Kindle 3 3G US "update_fonts_5.7.N_k3w_install.bin" - Kindle 3 WiFi "update_fonts_5.7.N_k3gb_install.bin" - Kindle 3 3G UK "update_fonts_5.7.N_k4_install.bin" - Kindle 4 (Silver & Black)
4) Place your preferred font set in the "linkfonts/fonts" folder. If you are asked if you want to overwrite files that are already in that folder, say "yes". The blue highlighted files (or those in the red box for K3) represent the font files that are replaced. NiLuJe has re-named your new fonts with the same name as the ones that need to be replaced and as long as you say "yes" to the file overwrite, you should have no problem.
5) Safely eject your Kindle from your computer. To apply the update, on the Home screen, click Menu > Settings > Menu > Update Your Kindle. If "Update Your Kindle" is grayed out, you either did not put the bin file in the root folder or used the wrong file for your Kindle model.
6) Your new font is installed. Below is a comparison of the original Kindle font and Fontin2 (the font I use on my Kindle).
Anytime you want to change your fonts, add the new fonts to the "linkfonts/fonts" folder and just drop a blank "reboot" file in the linkfonts folder (By copying and renaming the existing "autoreboot" blank file, for example) and you'll be good to go.
To remove the font hack, just copy the appropriate "uninstall" bin file to the root of your Kindle and update. Note that, since the v3.3.N, you shouldn't have to deactivate/uninstall it in order to be able to install official Amazon updates!
 How to Update the Fonts Hack
First of all, no need to touch the jailbreak again. You already installed it the first time you installed hacks. Just forget about it now ;).
Next, no need to run the update_*_uninstall.bin update, ever. (except in some very specific cases, like if you're updating from another font hack [in which case you should use the original uninstaller for your hack, and not the one found here]).
Then, you can apply the latest update_*_install.bin update.
After that, to make sure everything's in order, do a full Restart of your Kindle, and you'll be good to go.
Basically, just do a full install of the hack like described here, and then restart your Kindle (Menu > Settings > Menu > Restart).