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Polsia vs Castan in 2026: what each one does, what it costs, and who owns what

By Tudor Bungardean. Published 23 September 2026. Every outside fact read on 23 September 2026.

Polsia is an AI that builds and runs a company for you and acts on its own; Castan is an AI that runs the company you already have and acts after you approve. Both open with the same two doors, start a new company or bring one that already exists, and behind the doors they are different things. Polsia is an autonomous operator: agents build the site and the code, run ads and outreach, answer support, and choose the next action every night. Castan is a memory and a set of agents over the company you already run: it reads your Gmail, Slack, calls, invoices and GitHub, answers questions with citations, attends your calls, chases your invoices, and proposes the next step for you to approve. This article puts the two side by side on what they do, what they cost, how much they do on their own, and who keeps what. Castan wrote it, so read the Polsia column against the sources at the end.

Polsia vs Castan in one table

Read on 23 September 2026 from each product’s published pages
PolsiaCastan
What it isAn AI that builds and runs a business: site, code, ads, outreach, support, a nightly reportAn AI that builds and runs your company with you: one memory over your own accounts, a meeting assistant, invoice chasing, agents that propose and act with approval, software and idea pages built into your repo, an interview after every sign-up, any MCP server connected
Who it is forAnyone with an idea, and existing businesses that want it run for themFounders with an idea, and small operating teams that want the company remembered and the follow-through done
Price$20, $50, $100 or $200 a month, plus task tiers to $999$29, $99, $299 or $599 a month per workspace, free tier to start
Fees on your business3% of customer payments, 20% of ad spendNone: the flat price is the whole bill
Per personPlans are per account with one to three companiesNever per person; a workspace is one price whoever is in it
AutonomyFully autonomous: agents act and report the next morningApproval first for anything that reaches a customer or leaves the workspace; internal steps can run on their own when you switch them to auto
Where the code livesOn Polsia; a copy can be downloaded, no git access, no self-serve deploy elsewhereIn your GitHub repository, as pull requests you merge
Where the data livesOn Polsia’s platform, with a licence to train on your inputsIn your own Gmail, Slack, calendar and books; Castan indexes it and never trains on it
Your domainRegistered in Polsia’s name for the first 60 days when bought through PolsiaYours; hosted idea pages sit on a Castan subdomain until you attach your own domain, which you keep
RefundsNone for subscriptions, credits, domains or ad spendEU consumers keep the statutory right of withdrawal; cancel any time from Billing
Hosting regionNot stated on the pages we read; a subprocessors page is publishedEuropean Union: application in Amsterdam, database in Frankfurt
Languages on callsNot offered on the pages we readCalls transcribed in the language spoken, detected rather than chosen, from the Founding plan up

Autonomy: what happens while you sleep

This is the real difference. Polsia’s promise is that the agents do everything and you read about it in the morning. Users like the nightly email; the complaints, in Polsia’s own community and in reviews, are about work marked complete that did not happen and outreach sent under the customer’s name without their approval. Polsia’s founder wrote in April 2026 that the platform had become a spam machine and capped outreach at two emails a company a day.

Castan draws the line at the door. Anything that reaches a customer, a candidate or the public, an email, a chaser, a published page, a pull request, is proposed and waits for a person to approve it. Internal work, notes from a call, a task list, a page of what was promised and to whom, can run unattended when you switch that agent to auto. Castan also records every run with what it did, so a task marked done links to the thing that was done.

Outcomes, in the founders’ own words

Polsia reported crossing $1M of annual run rate in March 2026, then a $30M round at a $250M valuation in May 2026 with about $10M of run rate. In the same month its founder said in an interview that about one company in ten built on the platform had earned a dollar, and that he was losing money on every customer at the time. Castan went live on 6 September 2026 and is early: it publishes its plan, its prices and its security page, and this blog will carry its numbers as they come.

Polsia or Castan: which one to choose

  • You want a business made and operated for you, you accept that it runs under Polsia’s name and on Polsia’s platform, and you are comfortable with fees on payments and ads: Polsia.
  • You already run a company, or you are about to, and you want it remembered and followed through, with you approving what goes out: Castan.
  • You want to keep the code and the data whatever happens to the vendor: Castan writes code into your repository and reads data that stays in your accounts.
  • You want to test cheaply: Castan’s free tier indexes 200 items per source and captures one call a month; Polsia has no free trial as of September 2026.

Prices and terms change. If anything here is out of date, write to hello@castan.ai and we will correct it with the date of the change.

Questions people ask

Is Castan a Polsia alternative?

For a founder with an idea, yes: both open with a path for a new company. For a company that already exists, Castan is a memory and agents over your own accounts, while Polsia runs the business on its own platform. They overlap on the buyer, not on the product.

How does Castan handle outreach and follow-ups?

It drafts the message with the context behind it, proposes it, and sends it when you approve. Invoice chasers, follow-ups after a call and replies to an email all run this way, and internal steps such as notes and task lists can run on their own when you switch them to auto.

Who owns the code each product writes?

Polsia lets you download a copy of the code but gives no git access and no self-serve way to deploy it elsewhere. Castan writes code as pull requests into your own GitHub repository.

Is Polsia or Castan cheaper?

Polsia’s entry plan is $20 a month against Castan’s $29, but Polsia adds 3% of the payments your company receives and 20% of the ad spend it runs. Castan has no fees on your business and a free tier.

What is the difference between Polsia and Castan?

Polsia makes and operates a business for you on its own platform and acts without asking; Castan builds and runs the company you own, in your own accounts, and acts after you approve. Polsia launched in late 2025; Castan went live on 6 September 2026.

Sources

Also on the blog