Prospero

What it is

Prospero is a library, a writing studio, and a community for fiction and fanfiction, on the web. The home page's line is "Conjure the story. Keep the pen." The about page says you can write entirely by hand, or use the optional AI tools, and that the label tells readers which it was. The app lives at prospero-app.arabesque.social. The marketing site is prospero.arabesque.social. One Google account is described as working across Prospero and the other Arabesque sites: Arabesque, Kolo, Liminal, Vuelta, and Tutti.

This review is based on public pages, not tested with an account. Last checked 27 October 2026. We did not sign in, start a book, or ask a model for a paragraph. Nothing here is a grade of the prose.

The privacy page says Arabesque is run by Valentin Sarić, in Zagreb, Croatia, and links valentinsaric.com. The footer names the same person and city, and calls Prospero a sister site. Terms and privacy are both dated 17 October 2026. Those pages do not give a launch date. On 27 October 2026 the public library listed 49 books. Every one of them is by Valentin Saric, handle valentinsaric1. The oldest update time on that list was 20 October 2026. That is a timestamp on a record, not a published launch date.

Full disclosure: I also build ProseEngine, an AI fiction-writing tool listed on the same terms as everyone else.

Who it's for

• People who want to publish chapter by chapter, originals or fanfiction, and who want readers to see a label for how the chapter was made. The home page compares the library with Wattpad and the studio with a writer's desk.
• Writers who want the model quiet until they ask. The about page says you write by hand or use the optional tools. A human mode on the book page says you write every word, and that AI only checks or polishes when you ask.
• Readers who want the label before the chapter. The home page says you choose what you read. The app's own invite text says the library can be filtered to human-written, AI-assisted, or AI prose.

It is a weak fit if you need a local file, a model that runs on your machine, or a key from your own provider account. None of those is on the public pages. It is a weak fit if you wanted to sell fanfiction. The publish screen says fanfiction can be shared and cannot be sold. It is also a weak fit if you are under 16. The terms, and the sign-in box, say you must be 16 or older. Mature books add a second line: readers sign in and confirm they are 18 or older.

Key features in practice

The features below are what the home page, the about page, the plans page, the terms, the privacy policy, and the public config say the product does. They are the vendor's description. This review did not click them inside an account.

• Library, studio, community. Open the app and the library is the front door: shelves, genres, and a reader with a cover, a blurb, and chapters. Paid chapters, the home page says, show a preview first. The studio starts in Fun mode (an idea, a genre, go) or Serious mode, with prep phases. The community is posts, follows, messages, and groups. There is a report control and a block control. The home page says there are no ads and no tracking.
• Prep phases. Premise, characters, world, voice, and outline. The about page says you can rename, reorder, skip, or add phases, and write each one yourself or have AI draft it. The public model list describes what each default phase asks for: a logline, a cast with a want and a wound, the rules of the place, a voice sample, and a numbered chapter outline.
• Optional chapter AI. The model menu, from the public genres endpoint on 27 October 2026, lists free models and paid ones. Free: Gemma 4 31B and Gemma 4 26B, marked Google via OpenRouter, and GPT-OSS 120B on Cloudflare. Paid: DeepSeek V4 Pro, DeepSeek V4 Flash, Kimi K2.6, Qwen 3.5 122B, MiniMax M2.5, Mistral Small, and GPT-OSS 120B again, this time not on the free Cloudflare path. "Recommended" means Prospero picks for your plan. A separate 18+ pair, Dolphin Venice and a mix that uses Dolphin only for intimate scenes, is marked uncensored and limited to Mature books. The menu locks the paid models until the plan is paid, and it locks Dolphin until the book is marked Mature.
• A checker for AI habits. The about page says open models draft and a stronger model checks for AI habits: stock phrases, flat rhythm, tidy morals. The home page's checker line says stock phrases, flat rhythm, and em-dash storms, plus a prose score. Refine buttons on the marketing page include remove AI habits, vary rhythm, show don't tell, sharper dialogue, tighten, more vivid, or your own words. Quality mode, the home page says, is a writer model, then a checker, then a revision before you see the draft. A note in the app says quality mode counts a chapter twice against the daily chapter cap.
• Named AI jobs. The same public list names the jobs: writing chapters, prep phases, checking for AI habits, refining passages, ideas and brainstorming, story memory (chapter summaries), and an AI-share judge. Memory is described as summarising earlier chapters so a new chapter can continue. The judge reads the book for the label.
• The AI-share label. The publish screen says the label is measured from what you did: your idea, your prompts, prep you wrote, how much AI wording survived your edits, plus a judge model reading the prose. The badges the library actually returned on 27 October 2026 included "Human-written" and several "AI prose" lines, one of them "AI prose · from the author's 5-word idea." Of the 49 public books, 14 had a label and 35 came back with none. The library's own count calls those 35 unmeasured. The product says every book carries a label. On that day, most of the public shelf did not have one yet.
• Publish, sell, export. Originals can mix free and paid chapters. The sell panel says you set the price and the shop (Gumroad, Ko-fi, Payhip, Patreon, Amazon KDP, or your site), that money goes straight to you, and that Prospero takes nothing. Readers of a paid chapter see a preview, a buy button, and a box for an unlock code. Fanfiction is always free. The export line says the file carries a disclosure that it was made with Prospero and states the AI share, which the page says KDP asks you to declare, and that fanfiction can be shared but not sold. Download buttons listed on the page: PDF (called a 6×9 print-ready book), EPUB, Word, TXT, and Markdown. On 27 October 2026 every public book had a price of zero. The paid-chapter path was described. It was not in use on that shelf.
• Translations. A book stays in its original language. A translation is a separate edition. The reader banner on a translated chapter says "AI translation," names the model, and offers the original. If a reader started it, the banner adds "made for a reader." The language menu for translation has 28 languages. The story-details menu, for the language of the book itself, lists 29 languages plus Other. The interface of the pages we read is English.
• Covers and Galatea. Galatea is the named assistant: craft talk, ideas, community drafts, and covers. Cover painters in the public list include free Cloudflare models (FLUX, Leonardo's Lucid Origin and Phoenix, SDXL) and paid OpenAI image models. The home page says you approve what she drafts, and that AI-assisted work is marked.
• Sign-in and install. The FAQ says you sign in with Google, and that there is no password. The home page tells you to install the site from Chrome, Safari, or Edge so it opens like an app. It also offers a Mac download, Apple Silicon and Intel, macOS 12 or newer, and says Apple has not checked it. An Android package was at the download address on 27 October 2026. The static sentence on the page still says the APK will be available soon. The page's own script is written to replace that sentence when the file is present. We did not install either file.

Pricing (checked 27 October 2026)

The figures are on the plans page inside the app, which reads the public config. The home page shows the same three euro prices and a shorter list. Limits below are per day.

Plan	Price	What the plans page lists
Free	€0	3 new books, 6 chapters up to 1,500 words, 40 AI helps (prep, ideas, refine, check), 3 covers with the free painters, open models, export, community. Prospero chat: 10 messages a day
Writer	€2.99/month or €24.99/year	10 new books, 25 chapters up to 2,500 words, 200 AI helps, 12 covers a day of which 4 use OpenAI's paid painters, stronger writer and checker models, Mature writer for adult books, Prospero chat with Gemini: 50 messages a day
Studio	€7.99/month or €69.99/year	30 new books, 80 chapters up to 5,000 words, 600 AI helps, 40 covers a day of which 12 use the paid painters, the strongest checker in quality mode and for continuity checks, Prospero chat with Gemini: 150 messages a day, a Studio badge

The plans page has a yearly tab labelled "2 months free." Writer at €2.99 times 12 is €35.88. The yearly price is €24.99, which is €10.89 less, about three and a half months, not two. Studio at €7.99 times 12 is €95.88. The yearly price is €69.99, which is €25.89 less, a bit over three months. The slogan and the arithmetic do not match. The euro amounts themselves are printed, in the config and on the cards.

The terms say paid plans renew monthly or yearly through Polar until you cancel, and that you keep the plan until the end of the period you paid for. They say prices include VAT where it applies. The plans page says Polar (Polybook Press) handles the card, that you should use the same email as your Google sign-in, and that the Writer plan is the same plan as Arabesque's Dancer, so one payment covers the other Arabesque sites. The home page adds a founding-writer offer: join before 1 March 2027 and keep, for life, 8 pictures per post, saved Galatea chats, PDF export, weekly backups, and a badge. Those extras are community limits, not a fourth writing price.

A continuity check sits in the book tools on the chapter screen. The plans page is the page that ties "the strongest checker" for that check to Studio. Whether Free runs a weaker check is not stated there.

What this review did not do

There is no hands-on section. We did not open an account, paste a chapter, run the checker, buy a plan, or install the Mac app or the Android package. The scores further down are an editorial reading of the public offer: how specific the label is, how plain the prices are, and how much the terms leave unsaid. They are not a measurement of prose.

Using it as a writer

1. Read a public book before you sign in. The library does not ask for an account. On 27 October 2026 the shelf was 49 books by the founder, 40 of them fanfiction and 9 originals. Use one that already has a label, and one that does not, and see whether the badge matches the chapter.
2. Read the privacy page before a manuscript you have not published. It names Gemini, through OpenRouter, for what you type to Galatea. It does not name the chapter models, and it does not say whether those providers keep the text or train on it.
3. Decide the mode before the first chapter. Human mode is the one that says you write every word. Fun mode and Serious mode are the ones that draft. The label is supposed to follow what you actually did, including polish you keep.
4. If the book is fanfiction, assume it cannot be sold here. The publish screen says so. The terms do not discuss franchise copyright, and the only removal route they describe is the report button. That is a gap, not a licence.
5. Read the yearly tab against twelve times the monthly price on the day you pay. The page says two months free. The config's yearly totals are lower than that slogan by more than two months.

Strengths

• AI is described as optional, in the about page and in a human mode. You can write the chapter. The checker and the refine buttons are things you press.
• The label is a real field, not only a slogan. The library returned "Human-written" and several precise "AI prose" lines, including one that counted a five-word idea. Fourteen books had a label on the day we read the shelf.
• The prices and the daily caps are numbers. €2.99, €24.99, €7.99, €69.99, and the book, chapter, word, and AI-help caps, in the public config and on the plans page. You do not have to guess the Writer number.
• Selling originals is pointed away from the platform. Money goes straight to you. Prospero takes nothing. Export is PDF, EPUB, Word, text, and Markdown, with a disclosure line the page says is for KDP.
• Translations are marked. A translated chapter says it is an AI translation, names a model, and links the original.
• The operator is named. An individual in Zagreb, a date on the terms, Polar named for the card, and no ads or tracking pixels in the privacy page.

Weaknesses

• Training and retention for the chapter models are not stated. The privacy policy names Cloudflare for hosting, OpenAI for moderation only, Polar for payment, and OpenRouter with Google Gemini for Galatea chats and drafts. Gemma, DeepSeek, Kimi, Qwen, MiniMax, Mistral, the paid GPT-OSS path, and Dolphin Venice are not in that list. The policy does not say whether text sent to them is kept or used for training.
• The terms do not discuss fanfiction. They say your content stays yours, and that you give Arabesque permission to show it on the site and in shares you make. They do not mention derivative works, a franchise, or a copyright takedown path. The removal tool they describe is the report button on a post or a profile. Forty of the 49 public books are fanfiction of commercial franchises.
• Most of the public shelf had no label yet. Thirty-five of 49 books came back without an AI-share label. The page says every book carries one. A label that is missing on the shelf is not yet the promise on the about page.
• "Two months free" is not what the yearly totals are. The euro prices are clear. The discount slogan is not. Check the yearly tab.
• The terms and the Mature writer do not use the same rule. The terms forbid nudity in the "be kind" list and say posts that break it are removed. The studio offers an explicit Mature mode, 18+, with an uncensored model. Both texts are on the site. A writer posting an excerpt should read both.
• The library is one author. Forty-nine public books, all by the founder. That is a working shelf, and it is not yet a community of writers. No independent review was found on 27 October 2026. Searches that day returned other products named Prospero, not this one.
• One sign-in, and it is Google. There is no password account on the FAQ. If you will not use Google, the pages do not offer another door.
• The Mac app is not checked by Apple, and the page says so. The Android package was on the download URL while the static sentence still said soon. We did not install either one.

How it compares

• Prospero vs Sudowrite. Sudowrite is a prose studio: continuation, description, rewrite, and a story bible, on a monthly credit subscription. Prospero will draft a chapter if you ask, and it also keeps a public library, a fanfiction shelf, and a label for readers. If the blank page is the problem and you do not want a public chapter page, Sudowrite is the closer tool. If you want the chapter online with a badge that says how it was made, that is the job Prospero is claiming. See the Sudowrite review.
• Prospero vs Novelcrafter. Novelcrafter's codex is a database you maintain, and from the Hobbyist plan up you bring your own key, including a local model. Prospero includes the models, with a daily cap, and does not offer a key or a local model. The prep phases are a short studio, not that codex. See the Novelcrafter review.
• Prospero vs Creader. Both are browser tools for long fiction with a check you can run. Creader extracts a world memory from the prose and sells the check as Guardian. Prospero's checker, as described, hunts AI habits and can run a continuity pass, and the thing the pages spend more words on is the public library and the AI-share label. Creader's privacy policy names which providers may train. Prospero's does not name the chapter models. See the Creader review.
• Prospero vs ProseEngine. Full disclosure: I also build ProseEngine, an AI fiction-writing tool listed on the same terms as everyone else. It is a fiction studio with a codex and scene generation, priced in euros, with a free plan. We are not scoring that matchup.

Verdict

On the pages, Prospero is a real library and a real studio, run by a named person in Zagreb, with a free plan, two printed prices, a human mode, and a label that at least some public books already carry. The limits are the ones to read twice. The privacy policy does not say whether the chapter models keep your text or train on it. The terms do not discuss fanfiction, and the public shelf is mostly fanfiction, all of it by the founder, most of it still without a label.

Use the library, which does not ask for an account, before you connect Google. Do not put an unpublished book into a chapter model until you have decided you can live with a privacy page that does not mention that model. Do not buy the year because a card says two months free. Read the yearly total. And do not treat a missing label as a promise that the chapter was written by hand.

The scores are a reading of that public offer. A later independent review, or a shelf that is not one author, could land somewhere else.

FAQ

Is Prospero free? Reading is free. A free plan can start books: 3 new books a day, 6 chapters a day up to 1,500 words, and 40 AI helps a day, on open models, with no card. Sign-in is Google. You must be 16 or older.

How much is Writer, and how much is Studio? On 27 October 2026 the plans page and the public config said Writer was €2.99 a month or €24.99 a year, and Studio was €7.99 a month or €69.99 a year. Writer raises the daily caps to 10 books, 25 chapters of 2,500 words, and 200 AI helps, and lists stronger models and a Mature writer. Studio raises them to 30 books, 80 chapters of 5,000 words, and 600 AI helps, and lists the strongest checker, including for continuity checks. The terms say prices include VAT where it applies. Polar bills the card. The page calls the yearly tab two months free. Twelve times the monthly price minus the yearly price is more than two months.

Does Prospero train on my manuscript? Not stated. The privacy policy of 17 October 2026 says what you type to Galatea is sent to OpenRouter and Google Gemini. It names OpenAI for moderation only. It does not name the chapter models, and it does not say whether text sent to them is kept or used for training.

Do I own what I write there? The terms say your content stays yours, and that you give Arabesque permission to show it on the site and in shares you make. They do not mention fanfiction or derivative works. The publish screen says you may sell originals elsewhere, that Prospero takes nothing, and that fanfiction can be shared but not sold. Export is described as carrying a disclosure of the AI share.

Can I write without the AI? The about page says yes. Write entirely by hand, or use the optional tools. Human mode on a book says you write every word, and that a check or a polish runs only when you ask. Polish you keep counts toward the AI-share label.

Are there independent reviews? None found as of 27 October 2026. Results for the name Prospero that day were other products. The public library was 49 books, all by the founder.