Free & Open Source

Where Stories
Come to Life

One app to write, organize, and publish your novel. Stop juggling five tools — craft your next masterpiece in one place.

Windows · macOS · Linux v1.0.0 · 48 MB · No account required
The night sky stretched infinitely above the old lighthouse, each star a pinprick of ancient light. Clara pressed her forehead against the cold glass and wondered if anyone else in the world was looking at the same constellation.

Everything You Need to Write

Powerful tools wrapped in a clean, minimal interface that stays out of your way.

Distraction-Free Editor

A minimal writing surface that keeps you focused on words, not toolbars. Fullscreen zen mode included.

Manuscript Organization

Chapters, scenes, and notes in a drag-and-drop outline panel. Restructure your story in seconds.

4-Stage Workflow

From messy ideas to polished manuscript: Braindump, Outline, Prose, Format. A clear path from spark to finished draft.

Story Bible

Track characters, locations, and lore across your entire manuscript. Never lose a detail again.

Mind Maps & Linking

Visualize your story structure and link ideas directly to your prose. See the big picture without losing the thread.

Offline First

Works without an internet connection. Your data stays on your machine — no cloud required.

Writing Goals

Set daily word-count targets and track streaks over time. Build the habit that finishes books.

Themes & Typography

Dark mode, sepia, and custom fonts so the editor feels like yours. Easy on the eyes, day or night.

Export Anywhere

Export your manuscript as PDF, EPUB, DOCX, or Markdown. Take your work wherever publishing takes you.

See It in Action

A clean interface designed for writers who want to focus on the story.

Editor View

Clean, minimal writing surface

Outline Panel

Drag-and-drop chapter management

Dark Mode

Write comfortably at any hour

A Council of Second Opinions

Stuck on a scene? Ask multiple AI models for suggestions, compare their takes, and pick the one that fits your voice. You stay in control — always.

Council of LLMs

Ask multiple AI models the same question and compare their answers side by side. Pick the best, discard the rest.

Bring Your Own Keys

Use your own API keys from the providers you trust. You choose the models, you control the cost. No middleman markup.

Professional Book Formatter

Stop paying $150+ for a separate formatting app. Nebula handles the entire journey from draft to publish-ready file — built right in.

Professional themes
Choose from book-interior templates designed for print and digital
PDF & EPUB export
Publication-quality output ready for KDP, IngramSpark, or any retailer
Front & back matter
Title pages, copyright, dedication, about the author — all handled
ISBN support
Embed your ISBN and generate barcodes for print-ready covers
Book Formatter
PDF
EPUB
DOCX
Theme: Classic Serif
Chapter One
The night sky stretched infinitely above the old lighthouse, each star a pinprick of ancient light...

Write from Anywhere
with Nebula Cloud

The hosted version of Nebula — no install required. Start writing in seconds from any device.

Real-time sync
Seamlessly across all your devices
Automatic backups
Version history so you never lose a word
Collaborate in real time
Invite editors and co-authors
Pay only for months you use
No subscription lock-in — skip a month, pay nothing
Try Nebula Cloud
cloud.nebula.app
All Projects Novel Draft Research
The morning light filtered through the curtains, casting long shadows across the manuscript pages scattered on the desk. She picked up her pen, took a breath, and began to write again.
Saved · 1,247 words 2 collaborators

Simple, Honest Pricing

The desktop app is free forever. Cloud plans only bill for the months you actually use.

$0
forever
  • Full desktop app
  • All writing & organization tools
  • Offline first — your data stays local
  • Export to PDF, EPUB, DOCX
  • Open source (MIT)
Download
Recommended
$9/mo
only months you use
  • Everything in Free
  • Nebula Cloud access
  • Real-time sync across devices
  • Automatic cloud backups
  • AI Assist & Council of LLMs
Get Started
$19/mo
only months you use
  • Everything in Premium
  • Real-time collaboration
  • Professional book formatter
  • Publishing integrations
  • Priority support
Get Started

Transparent by Default

Fully Auditable

Every line of code is public. Review it, fork it, or contribute.

No Telemetry

No tracking, no analytics, no data collection. Your writing is yours alone.

No Lock-In

Standard file formats. Export everything. Switch tools anytime.

Licensed under the MIT License. See our open source dependencies

Frequently Asked Questions

Yes. The desktop app is completely free and open source under the MIT license. Nebula Cloud is a paid service, but you only pay for the months you actually use — no long-term commitment, no subscription lock-in.

Nebula runs natively on Windows, macOS, and Linux. Nebula Cloud works in any modern web browser — Chrome, Firefox, Safari, and Edge.

The desktop app stores everything locally on your device — we never see it. Nebula Cloud stores data in encrypted AWS infrastructure. You own your data and can export or delete it at any time.

Yes. Nebula can import DOCX, Markdown, and plain text files. Formatting and structure are preserved where possible, so you can pick up right where you left off.

Nebula is a writing tool first. AI features are optional and never in your way. If you choose to use them, you bring your own API keys and pick which models to use — we don't mark up costs or lock you into a single provider. Your writing is always yours.

Nebula is maintained by a small independent team of developers and writers. The project is open source, so anyone can inspect the code, report issues, or contribute improvements.

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