Both tools live in the same category and lean in opposite directions. Sudowrite is built to generate prose with you. Vellam is built to read the prose you write, check it across the whole book, and help you write it yourself without putting words on the page for you.
You can write a novel in either one. The real question is what you want the tool to do while you do it: produce the prose for you, or read and check the prose you produce.
Short answer: Sudowrite is a generation-first co-writer. Vellam is an analysis-first writing tool: it reads your manuscript, tracks it, flags what does not hold together, and its AI helps with ideas, not finished prose you paste in. Choose Sudowrite if you want the AI to write. Choose Vellam if you want to write your own and have it read closely.
What each tool is built around
Sudowrite is a generation-first co-writer. Its core motion is producing text: expanding a scene, suggesting the next paragraph, rewriting passages in different styles. It does this in real depth, and that is the product.
Vellam is an analysis-first writing tool. You write in its built-in editor, and the centre of the tool is the analysis layer: it reads your manuscript chapter by chapter, builds a map of every character, location and thread, checks consistency across the whole book, and even tells you how AI-like the prose reads. Its AI assistant brainstorms ideas with you, but it never writes the book for you.
Functional comparison
| Capability | Sudowrite | Vellam |
|---|---|---|
| AI writes finished prose for you to use | ||
| AI brainstorms ideas and plot directions with you | ||
| Reads your whole novel chapter by chapter, remembering what came before | ||
| Whole-book consistency check (character, location, plot contradictions) | Vellam only | |
| Auto-built Story Atlas (per-chapter cards from your text) | Vellam only | |
| Character, location and plot heatmaps across chapters | ||
| Auto-extracts characters, locations and plots from each chapter | ||
| Built-in AI-writing detector (per chapter and whole book) | Vellam only | |
| Rule-based prose analysis, no credits (cliches, passive, weak verbs, repetition) | ||
| Long-form developmental critique of the whole book | ||
| Inline comments and shared review with reader roles | ||
| Daily writing goals and streak tracking | ||
| Fully localized interface (Polish, English, German, Spanish) | ||
| Your manuscript is never changed for you | ||
| One-time payment, credits never expire |
A check marks the tool built for that job. Sudowrite leads on writing prose for you. Vellam leads on reading, checking and localizing, and on keeping every word yours.
The things Vellam does that a generator does not
It reads and checks the whole book
Vellam reads your manuscript chapter by chapter, the way a reader does, keeping every prior chapter in mind. From that it runs a whole-book consistency check and flags four kinds of contradiction: a character trait, a character’s state of mind, a location description, and a plot status that stops adding up. A generator has nothing equivalent, because it is built to add text, not audit it.
It builds a Story Atlas from your text
After each chapter, Vellam generates per-chapter cards for every character, location and thread, pulled from what you actually wrote, with heatmaps that show where someone disappears for a stretch. Nothing to fill in by hand.
It tells you how AI-like your prose reads
Vellam has a built-in AI-writing detector. Run it on a chapter or the whole book and it scores how machine-like the writing looks, with the lowest-scoring sentences highlighted. It is the same kind of scan a publisher or contest might run, so you see it first. No generator ships this, for obvious reasons.
It checks your prose at the sentence level, for free
A rule-based analysis layer marks cliches, weak verbs, filler, passive narration and repetition, and it costs no credits. If your worry is generic writing, this is the part that helps you cut it, in your words.
An idea generator, not a prose generator
This is the important distinction. Vellam’s AI is a thinking partner, not a ghostwriter. The assistant brainstorms plot, talks through a character, and points at a line that could be sharper. What it does not do is hand you finished prose to drop into your book. There is no insert button, nothing is written into your manuscript, and the whole design assumes you write every line in your own words. Sudowrite is the opposite by design: it produces prose for you to keep. If you want the words in your book to be yours, that difference is the whole decision.
Built with authors and publishers, and it moves fast
Vellam is built in the open with the people who use it. There is a public feedback board where authors and publishers post requests, vote, and watch them ship, and we read and act on all of it. The roadmap is shaped by working novelists and by publishing houses at the same time, which is rare in this category, and features land quickly. The goal is the tool writers actually want, improved continuously with them, not an AI that writes the book in their place.
Works in your language
Vellam’s interface is fully localized in Polish, English, German and Spanish, and its analysis is built for manuscripts in those languages. Sudowrite’s interface is English, and its non-English support comes from the underlying model matching your language, with quality that varies. If you write in Polish, German or Spanish, that difference is not cosmetic.
You stay in control
Sudowrite generates prose, and generated prose carries the patterns of the model that made it, which is why some writers spend as long editing it as writing from scratch. Vellam never changes your text on its own. Its AI help is opt-in, sits in a side panel, and your text is not used to train any model.
Choose Sudowrite if
- You want the AI to write prose for you, in depth, especially against a blank page.
- You are comfortable with a subscription and an English interface.
Choose Vellam if
- You want to write your own novel, in your own words, and have the whole book read and checked.
- You want consistency tracking, a Story Atlas, an AI-writing detector and sentence-level analysis in one place.
- You write in Polish, German, Spanish or English and want a fully localized tool.
- You prefer a one-time payment with credits that do not expire.
Can you use both?
Yes. If a generator helps you get unstuck, draft with it, then run the finished manuscript through Vellam as a consistency, AI-detection and structure pass before it reaches a beta reader or an editor.
Frequently asked questions
Does Vellam write prose for me?
No. Its AI is an idea generator: it brainstorms and points at lines to improve, but it never hands you finished prose to paste in. You write every line in your own words.
Does Vellam have an AI detector like a standalone checker?
Yes. It scores how AI-like a chapter or the whole book reads and highlights the lowest-scoring sentences, so you see what a publisher’s scan would see.
Does Vellam work for novels written in Polish, German or Spanish?
Yes. The interface and the analysis are built for Polish, English, German and Spanish. Most competitors are English-only or rely on the model to improvise other languages.
Will Sudowrite output read like AI?
Generated prose carries the patterns of the model that produced it. Vellam’s built-in detector exists precisely so you can check that before anyone else does.