Feature · Bring your own API key
Connect one OpenRouter key and AIWriteBook runs your chapters, outlines, covers and images on it. Each action that runs on your key costs 1 credit, and OpenRouter bills you directly for the model. For chapters you can pick any of the 100+ text models on OpenRouter.
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What this key covers
Most AI book tools make you choose: either you use the models they picked and pay their prices, or you manage raw API keys yourself and get a blank text box. AIWriteBook works without a key, on credits, with Gemini, Claude and Grok built in. The key is an option for authors who want more control over the model and the bill.
If you have used a key-first tool such as NovelCrafter, the difference is that here the key is optional and plugs into the full workflow: outline, story bible, chapters, cover, formatting and publishing. If you are still comparing tools, our guide to the best AI writing tools for authors covers how the options differ.
One OpenRouter key covers the writing and the pictures. A separate, optional ElevenLabs key covers audiobook narration.
Chapter drafts, rewrites, outlines and every other text action in the app run on your OpenRouter key.
When you write or regenerate a chapter, open "All other models" and pick any text model in the OpenRouter catalog. The rest of the app keeps the models AIWriteBook chose, billed through your key.
The reasoning models used for complex chapters also run on your key, so long, tangled chapters are billed to your OpenRouter account.
Book covers and chapter images are generated through your key, at 1 credit each instead of the normal price.
Character and world images, the style image, page illustrations, image edits, covers and translation each cost 1 credit when your key does the work.
Add an ElevenLabs key with Text to Speech access and your audiobooks are narrated on it. Without it, narration runs on our keys at the normal credit price.
Setup happens once, on OpenRouter and in Settings. After that, every action tries your key first.
1.OpenRouter account
Sign up at openrouter.ai with Google or email, open Credits and buy credits. Turn on Auto Top Up too, so a long book never stops halfway because the balance ran dry.
2.API key
In API Keys, click New Key, name it something like "AIWriteBook" and copy the key that starts with sk-or-v1-. OpenRouter shows it only once.
3.Settings
Save the key and AIWriteBook runs a live check against OpenRouter. You get a status for each thing the key is used for: covered, not covered, or not verified, with the reason and the fix when something is missing.
4.Chapter model
In the chapter model picker, open "All other models", search the catalog and click "Check and use this model". A quick live check confirms the model works with your key before the chapter is written.
The built-in picker offers Gemini, Claude and Grok. With your key, the same picker opens the whole OpenRouter catalog: families from Anthropic, OpenAI, Google, Meta, Mistral, DeepSeek and more, filtered to models that produce text. You choose per chapter, so one chapter can try a new model while the rest of the book stays on the one you trust.
Model families on OpenRouter
Model for this chapter
1 credit per chapter. You pay OpenRouter for the model itself.
Both ways write the same books with the same workflow. What changes is where the model cost lands and which models you can pick.
Six things worth knowing before you connect a key.
The 1-credit price applies when the action actually runs on your key. If an action includes a step that has to run on our keys, the whole action is charged at the normal credit price.
Once the OpenRouter key is connected, every action that can use it runs on it.
If OpenRouter rejects the key, it is disabled or it is out of credit, the action stops with an error instead of quietly running on our keys, and no credits are charged. Top up or re-enable the key, or remove it to go back to credits.
A balance of 0 credits blocks actions even with a key connected, so keep a small credit balance on your plan.
After you save it, the key is never shown back to you, only a masked hint with its first and last characters. Replace or remove it at any time.
If the key cannot do something, the status says why, such as a key limited to certain models or an account with no credit, and what to change in the OpenRouter console.
Most authors write on credits and never need a key. These are the ones who do.
You have credits there for other projects. Your book can use the same balance instead of a second model budget.
You found a model whose prose you like, or one that handles your genre better. Write your chapters with it inside the full book workflow.
Agencies, ghostwriters and series authors who run many chapters and rewrites. At 1 credit per action, the model cost sits on an OpenRouter bill you can watch and top up yourself.
Bring your own API key is part of the Ultra plan. Everyone else writes on credits with the built-in models, and can move to Ultra when they want their own key.
I am currently testing AIWriteBook to finish one of my unfinished books, and it's been amazing! The writing quality is excellent and it even sounds like me. It's easy to use and I'll definitely be signing up.
Read the full review on Trustpilot
… What I like most is that it is not just a text generator. You get a complete workflow - from the initial idea, characters and outline all the way to chapters, metadata and the cover. At the end you export files that are ready for Amazon KDP and KDP Print, in the correct formats and with the right dimensions. That takes a lot of fiddling out of the process. …
Read the full review on AppSumo
I bought @AIWriteBook to help with an existing historical novel, and my first impression is very positive. What I like most is that it isn't just a text generator. It combines manuscript import, characters, outlining, writing-style support, AI chat, chapter writing and editing in one environment. I can keep creative control while deciding how much I actually want the AI to help with the writing. …
Read the full review on TAAFT
I underestimated how helpful and useful AIWriteBook could be as a tool. When using the chapter by chapter editing, it not only suggested four ways to fix a passage, but why they were necessary. I plan to keep using this tool for a long time.
Read the full review on Trustpilot
… Then there's the audiobook feature, the reason I signed up in the first place. You take a finished manuscript and, with essentially the push of a button, it produces a full, professionally narrated audiobook. Natural sounding narration, real voice options, and it's all built for a distribution ready result, not just a rough recording. …
Read the full review on AppSumoMy overall experience is that it's a high‑quality product and I'm happy with my purchase. I would highly recommend it to anyone getting into writing or looking to refine a manuscript before it goes to print. …
Read the full review on Capterra
AIWriteBook really takes most of the hassle out of writing a book. It’s designed to help you by letting you import your Word drafts and then training the AI to match your voice across all your chapters, which seemed easy and I did not have any issues. That way, your tone stays natural and consistent from beginning to end. …
Read the full review on AppSumoI have more AI tools than I can count...literally. As far as book writers go this is the best I've seen if you care about quality. There are some decent ones out there you can churn out mid quality faster with, but nothing I've found that can come close to the quality you can get with this one. Great buy for the right audience.
Read the full review on AppSumo
Great tool to help write and edit your books. I especially like the cover creator. Has really helped me make some awesome-looking covers!
Read the full review on Trustpilot
I got this to make a personalised storybook for my kids. It worked well enough that I've made a few more since. The part I like is that you're not stuck with the first draft. You edit the outline, change the characters, rewrite a paragraph that reads wrong, and regenerate just that bit. Illustrations come out of the same flow, so there's no stitching images in from another tool. Export is a print-ready PDF, so the thing you end up with is an actual book you can get bound and wrapped. …
Read the full review on AppSumo
A writer's bestie, in all the ways that count. The best part is how easy it is to edit it your story, making it a complete, perfect blend that is something that's uniquely yours- integrating your own ideas, own special voice, and even unique quirks, while still enjoying the benefits of AI in all the aspects where you need it most- editing, readability, and idea prompts.
Read the full review on TAAFT
… My use case is strictly limited to travel non-fiction and I tested a few short stories with the Book Editor analysis. It’s brilliantly insightful and accurate; not dozy, vague suggestions like fix transition or blah-blah but deep actionable examples like an experienced human editor! …
Read the full review on AppSumo
… I am not using it for the whole write-a-book-from-scratch thing, but considering how much organization a technical non-fiction book can contain, it is helping me a lot, without losing my voice and tone. …
Read the full review on AppSumo
I bought AIWriteBook mainly to help build children's books and so far I am very impressed. The illustration quality is much better than I expected, with excellent detail, lighting and even reflections in objects such as balloons. It has also done a surprisingly good job of keeping my main characters and important story objects consistent between illustrations. …
Read the full review on AppSumo… It's way more app than anything else on the market. The developers clearly know what they're doing, and it fills a gap that virtually no one else does well. The inline editing is where books actually get good, and this is the first tool I've seen that takes that stage seriously instead of dumping a first draft on your desk and calling it done. …
Read the full review on AppSumo
I have tried several different tools that do specific tasks in fiction writing: editing, planning your book, formatting, writing, etc. This one tool provides these. Each function I have tried seems to provide good results and output. I am now revaluating the need of a couple of subscription-based tools I used thanks to this platform. …
Read the full review on AppSumoBeen toying with an idea for a book for about a decade, but never had the time to truly sit with it and dig in. After playing around with the settings and uploading my own style of writing as a voice, deeply impressed with how well it does keeping to my own style of writing. Already buzzing with more books in my head as i work on the first. Definitely happy i purchased.
Read the full review on AppSumo… One thing that really surprised me was when I imported an existing script that's at about 100,000 words. AIWriteBook not only did a good job at deciphering all the different characters, plots, and subplots, but to then put all of that in the correct places where they belong inside of the AIWriteBook application is just a phenomenal time saver and did a better job than the more established Sudowrite on the market. …
Read the full review on AppSumo
… Other users have already provided a detailed review, so I prefer to focus on an aspect neglected in their reviews: the audio recording options for the electronic book. Thus, I must say that the audio creation exceeds my expectations when I see the quality of the voices interpreting my fictional works (short stories) and ongoing developments (multi-voice readings). Bravo!
Read the full review on AppSumo
… The hard part comes when you read the chapter and think... this section needs to change, this part doesn't sound like me, or I want to take this in a different direction. This is where the book writing happens. AIWriteBook gets this part right. You can keep working on the chapter, make changes through the editor, regenerate weaker sections and continue refining the book instead of starting over every time. …
Read the full review on AppSumo
How the key, the credits and the models fit together.
You connect your own OpenRouter API key in Settings under Your Own API Keys. From then on, AIWriteBook runs your actions on that key: chapters, outlines, covers, chapter images and visual book images. OpenRouter bills you for the model usage, and each action that runs on your key costs 1 AIWriteBook credit instead of its normal credit price.
No. The settings page takes one OpenRouter key for writing and images, plus an optional ElevenLabs key for audiobook narration. OpenRouter is the route to the other providers: through it you can write chapters with models from OpenAI, Anthropic, Google, Meta, Mistral, DeepSeek and others, all on one key and one bill.
Yes, but far fewer. Each action that runs on your key costs 1 credit. If an action includes a step that has to run on our keys, it is charged at the normal credit price. Every action costs at least 1 credit, so a balance of 0 credits blocks actions even with a key connected.
For chapters, any text model in the OpenRouter catalog, which is more than 100 models. You pick it per chapter under "All other models" in the chapter model picker, and a live check confirms it works with your key before it is used. Outlines, covers and images keep the models AIWriteBook chose for those steps, billed through your key.
The action stops with an error instead of running on our keys, and no credits are charged for it. Buy more credits on OpenRouter, or remove the key to go back to writing on credits. Turning on Auto Top Up on OpenRouter keeps a long book from stopping halfway.
The key is stored encrypted and is never shown back to you. The settings page shows only a masked hint with the first and last characters, and you can replace or remove the key at any time.
Models on OpenRouter set their own content rules, and you choose the model for each chapter. If the model you picked refuses a scene, AIWriteBook tells you the request was refused and suggests picking a more permissive model, so you can switch and run the chapter again.
It is available on the Ultra plan. You can see what Ultra includes and compare it with the other plans on the pricing page.
On the AppSumo lifetime deal, Tier 3 and Tier 4 include bring your own API key. Tier 1 and Tier 2 do not.
The rest of the workflow your key plugs into.
Create a free account and write your first chapters with the built-in models. When you move to Ultra, connect your OpenRouter key and pick any model you like.
