Kobalt: an alternative reader app for Kobo devices

MrSilverstrike · Today, 05:25 AM

Hi everyone,

After many weeks of development and late nights, the first beta of Kobalt, my alternative reader app for Kobo devices (and soon, other devices too) is now available.

It works on most Kobo devices running firmware 4.x. It uses KOReader's CREngine under the hood (with some modifications). It's like a KOReader "Lite" in some ways, but with a more focused user experience.

For the KOReader diehards: it won't replace your favorite app. KOReader still has many more features and its plugin directory is, of course, unrivalled.

But for casual KOReader users who find the main app a bit too much, this might scratch a particular itch, like it did for me. (Or if you dislike the built-in reader app because its typography sucks. I made a mod for that too, as you might know. But that didn't go far enough. I had to make my own reader app!)

Also, unlike KOReader... Kobalt is more integrated into Kobo's OS: any DRM-free epub file can be opened in it via Kobo's "My Books" section (or your home screen). Purchased or loaned books work the same as before and open in the regular reader, as I don't want to have anything to do with DRM whatsoever. It's supposed to be pretty seamless!

You can visit the website to learn more or watch one or both of my two videos on the subject:

1. Why I decided to make Kobalt (mostly due to Kobo OS 6's slow reader, lol)

2. The beta you can try if you'd like

Let me know what you think!

Oh, it's all open source, too: https://github.com/nicoverbruggen/kobalt

Cheers,
Nico

P.S. I already have it working on Kobo OS 6 too, and on Android, but I'm releasing those later.

mrmikey · Today, 07:05 AM

No comment on the software yet but your description and narration is right on the money. I've never tried Koreader but I'm going to give yours a go for sure. I assume there's no interference with using Calibre? everything stays the same?
**EDIT**
Just installed, extremely easy to install, instructions were dead on, no hiccups at all, took all of about 2 minutes if that and everything worked as described right out of the gate.
I don't have the page turn animation but that is a deficiency of my reader, a Clara HD not Kobalt.
I have no complaints :-), my compliments for a nice bit of software.

MrSilverstrike · Today, 07:10 AM

Quote:

Originally Posted by mrmikey

No comment on the software yet but your description and narration is right on the money. I've never tried Koreader but I'm going to give yours a go for sure. I assume there's no interference with using Calibre? everything stays the same?

Everything stays the same, correct. If you have copied your books DRM-free to your Kobo (with or without converting to kepub) you should be set and have a good experience.

If you bump into any issues, feel free to comment in this thread or DM me.

Stevefj · Today, 07:26 AM

Is Wikipedia integrated into the app?

MrSilverstrike · Today, 07:42 AM

Quote:

Originally Posted by Stevefj

Is Wikipedia integrated into the app?

No, no Wikipedia integration (yet). I'll put it on the list.

mrmikey · Today, 08:03 AM

Just noticed also there's a % meter for the battery as well as the battery image, I like the percentage number being visible.

**EDIT**
Any way the % meter for the battery can be made an option to remain on the header, maybe replacing one of the other header displays?
Kobalt is very fast operating the books, page turns, opening etc.

JSWolf · Today, 08:18 AM

Can you fix Kobalt so it's more ePub3 compatible? The downside is that KOReader is not ePub3 compatible enough.

Apollyon202 · Today, 08:19 AM

I haven't tried yet, but will Kobalt's fonts conflict with my existing font folder? I have some custom fonts installed from your github (Newsreader for example), and some other sourced fonts as well.

rantanplan · Today, 08:48 AM

Do you plan to make the top header configurable? I prefer to have it set to remaining minutes in chapter instead of page progress. But it's just a small thing I can adapt to, I roughly know how many pages I can read per minute.

Looking forward to a 5.18.x / 6.x compatible version

PS
The best thing about Kobalt is that it doesn't sometimes clip the last line of a page on my Clara BW

.

MrSilverstrike · Today, 09:06 AM

Quote:

Originally Posted by Apollyon202

I haven't tried yet, but will Kobalt's fonts conflict with my existing font folder? I have some custom fonts installed from your github (Newsreader for example), and some other sourced fonts as well.

Fonts shouldn't conflict!

Quote:

Originally Posted by JSWolf

Can you fix Kobalt so it's more ePub3 compatible? The downside is that KOReader is not ePub3 compatible enough.

Please let me know what problems you seem to be having in terms of compatibility and I'd happily take a look. There are limits to what's possible with CREngine, though. Not making my own engine here. Ultimately, Kobalt is mostly a UI/UX project with some additional challenges.

As an aside: for proper ePub3 support, I'd argue that an E ink device is also not the right device (given the multimedia requirements).

Quote:

Originally Posted by rantanplan

Do you plan to make the top header configurable? I prefer to have it set to remaining minutes in chapter instead of page progress. But it's just a small thing I can adapt to, I roughly know how many pages I can read per minute.

Yes, header and footer customization is planned! Not sure if I'll have remaining time included, still investigating if I can come up with an approach that's more or less accurate. Kobo's often isn't.

rantanplan · Today, 09:21 AM

What’s the line height equivalent for 1.5 in Koreader expressed in percentage in Kobalt? I love that it’s so granular but I realized that I’m just fiddling around with it too much.

MrSilverstrike · Today, 09:43 AM

Quote:

Originally Posted by rantanplan

What’s the line height equivalent for 1.5 in Koreader expressed in percentage in Kobalt? I love that it’s so granular but I realized that I’m just fiddling around with it too much.

About that -- it's actually bugged right now, oops. 122% = 1.5 in KOReader at this point. I need to adjust it, because the calculation actually gets applied twice. See, this is why it's a beta

Gormagon · Today, 10:03 AM

Funny, Nico, just this Sunday I watched a youtube video where you demonstrated the Kobalt reader. If it's available as apk for Android I'll give it a try. I like KOReader but I don't need everything it has build in and it always takes some time opening with a library of >3000 files, it's faster when I've selected "start with last file". But then the app takes it's time when I want to see the library from within the last file. Maybe Kobalt can be faster. Librera for example is faster on all my devices.

rantanplan · Today, 10:11 AM

Is it possible to enlarge an illustration? In Nickel it’s doublepress, in KOReader it’s longpress but both don’t seem to do the job with Kobalt.

MrSilverstrike · Today, 10:18 AM

Quote:

Originally Posted by Gormagon

Funny, Nico, just this Sunday I watched a youtube video where you demonstrated the Kobalt reader. If it's available as apk for Android I'll give it a try. I like KOReader but I don't need everything it has build in and it always takes some time opening with a library of >3000 files, it's faster when I've selected "start with last file". But then the app takes it's time when I want to see the library from within the last file. Maybe Kobalt can be faster. Librera for example is faster on all my devices.

Want to take it for a spin? I just uploaded an early Android debug build.

Quote:

Originally Posted by rantanplan

Is it possible to enlarge an illustration? In Nickel it’s doublepress, in KOReader it’s longpress but both don’t seem to do the job with Kobalt.

Yeah, this is still missing right now.

Today, 05:25 AM	#1
MrSilverstrike Zealot Posts: 141 Karma: 969522 Join Date: Apr 2024 Location: Belgium Device: Kobo Libra Color, Kobo Clara Color	Kobalt: an alternative reader app for Kobo devices Hi everyone, After many weeks of development and late nights, the first beta of Kobalt, my alternative reader app for Kobo devices (and soon, other devices too) is now available. It works on most Kobo devices running firmware 4.x. It uses KOReader's CREngine under the hood (with some modifications). It's like a KOReader "Lite" in some ways, but with a more focused user experience. For the KOReader diehards: it won't replace your favorite app. KOReader still has many more features and its plugin directory is, of course, unrivalled. But for casual KOReader users who find the main app a bit too much, this might scratch a particular itch, like it did for me. (Or if you dislike the built-in reader app because its typography sucks. I made a mod for that too, as you might know. But that didn't go far enough. I had to make my own reader app!) Also, unlike KOReader... Kobalt is more integrated into Kobo's OS: any DRM-free epub file can be opened in it via Kobo's "My Books" section (or your home screen). Purchased or loaned books work the same as before and open in the regular reader, as I don't want to have anything to do with DRM whatsoever. It's supposed to be pretty seamless! You can visit the website to learn more or watch one or both of my two videos on the subject: 1. Why I decided to make Kobalt (mostly due to Kobo OS 6's slow reader, lol) 2. The beta you can try if you'd like Let me know what you think! Oh, it's all open source, too: https://github.com/nicoverbruggen/kobalt Cheers, Nico P.S. I already have it working on Kobo OS 6 too, and on Android, but I'm releasing those later.

Today, 07:05 AM	#2
mrmikey Connoisseur Posts: 50 Karma: 110 Join Date: Dec 2012 Device: Kobo Clara HD	No comment on the software yet but your description and narration is right on the money. I've never tried Koreader but I'm going to give yours a go for sure. I assume there's no interference with using Calibre? everything stays the same? EDIT Just installed, extremely easy to install, instructions were dead on, no hiccups at all, took all of about 2 minutes if that and everything worked as described right out of the gate. I don't have the page turn animation but that is a deficiency of my reader, a Clara HD not Kobalt. I have no complaints :-), my compliments for a nice bit of software. Last edited by mrmikey; Today at 07:25 AM.

Today, 08:03 AM	#6
mrmikey Connoisseur Posts: 50 Karma: 110 Join Date: Dec 2012 Device: Kobo Clara HD	Just noticed also there's a % meter for the battery as well as the battery image, I like the percentage number being visible. EDIT Any way the % meter for the battery can be made an option to remain on the header, maybe replacing one of the other header displays? Kobalt is very fast operating the books, page turns, opening etc. Last edited by mrmikey; Today at 08:58 AM.

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Today, 07:26 AM	#4
Stevefj Junior Member Posts: 1 Karma: 10 Join Date: Aug 2026 Device: Kobo H20,Kobo Forma,Sony Prs 950	Is Wikipedia integrated into the app?

Today, 08:18 AM	#7
JSWolf Resident Curmudgeon Posts: 85,289 Karma: 154365101 Join Date: Nov 2006 Location: Roslindale, Massachusetts Device: Kobo Libra 2, Kobo Aura H2O, PRS-650, PRS-T1, nook STR, PW3	Can you fix Kobalt so it's more ePub3 compatible? The downside is that KOReader is not ePub3 compatible enough.

Today, 08:19 AM	#8
Apollyon202 Addict Posts: 226 Karma: 251718 Join Date: May 2018 Device: Kobo Libra 2, Clara HD, Aura, Touch	I haven't tried yet, but will Kobalt's fonts conflict with my existing font folder? I have some custom fonts installed from your github (Newsreader for example), and some other sourced fonts as well.

Today, 08:48 AM	#9
rantanplan Weirdo Posts: 1,351 Karma: 13516840 Join Date: Nov 2019 Location: Wuppertal, Germany Device: Kobo Libra 2, Tolino Vision Color, reMarkable PaperPro	Do you plan to make the top header configurable? I prefer to have it set to remaining minutes in chapter instead of page progress. But it's just a small thing I can adapt to, I roughly know how many pages I can read per minute. Looking forward to a 5.18.x / 6.x compatible version PS The best thing about Kobalt is that it doesn't sometimes clip the last line of a page on my Clara BW .

Today, 09:21 AM	#11
rantanplan Weirdo Posts: 1,351 Karma: 13516840 Join Date: Nov 2019 Location: Wuppertal, Germany Device: Kobo Libra 2, Tolino Vision Color, reMarkable PaperPro	What’s the line height equivalent for 1.5 in Koreader expressed in percentage in Kobalt? I love that it’s so granular but I realized that I’m just fiddling around with it too much.

Today, 10:03 AM	#13
Gormagon monstrous mythical beast Posts: 204 Karma: 5078396 Join Date: May 2023 Location: Klopstokia Device: Tab Ultra C, Meebook P78 Pro, Viwoods AIPaper Reader, various NXTPAPER	Funny, Nico, just this Sunday I watched a youtube video where you demonstrated the Kobalt reader. If it's available as apk for Android I'll give it a try. I like KOReader but I don't need everything it has build in and it always takes some time opening with a library of >3000 files, it's faster when I've selected "start with last file". But then the app takes it's time when I want to see the library from within the last file. Maybe Kobalt can be faster. Librera for example is faster on all my devices.

Today, 10:11 AM	#14
rantanplan Weirdo Posts: 1,351 Karma: 13516840 Join Date: Nov 2019 Location: Wuppertal, Germany Device: Kobo Libra 2, Tolino Vision Color, reMarkable PaperPro	Is it possible to enlarge an illustration? In Nickel it’s doublepress, in KOReader it’s longpress but both don’t seem to do the job with Kobalt.