Custom AI agents for repetitive data work.
An AI agent is software that uses a language model to carry out a task on its own: for example, it reads an email or a document, pulls out the data, checks it against set rules and enters it into a system you already use. I build custom agents like this for businesses: each one handles one specific process, follows fixed rules and waits for a person to approve any step where a mistake would cost money. The consultation is free. If you then approve my quote or some of its parts, I build a free prototype on a sample of your data.
Ing. Patrik Krajňák, Full-stack developer, Košice
What an AI agent does in your business
In a business, an AI agent takes over the data work that someone currently repeats by hand and leaves only the exceptions to people. It runs on its own, for example every morning before the working day starts or whenever a new order comes in. When it isn't sure about a value, it leaves it out and asks a person instead. An agent can take over work like this:
- Morning reports waiting in your inbox before you get to work
- Processing orders and documents that arrive by email, as PDFs or through a web form
- Extracting data from PDF or scanned invoices and entering it into your accounting software
- Moving data between your online store, CRM and spreadsheets that don't talk to each other yet
How it works
How an AI agent handles a task
- 1
Input
An email, document, order or report that someone processes by hand today.
- 2
Reading
A language model pulls out the data in a fixed format.
- 3
Checks
Fixed rules verify the data and stop anything that doesn't add up.
- 4
Approval
Where a mistake would cost money, a person decides.
- 5
Entry
The agent enters the data into your system and logs every step.
Which business processes to automate first
The first thing worth automating is work that someone does the same way every time and could describe in a few rules. A typical example is an accountant who matches rows by hand in the same Excel file every month. Decisions that call for judgment or a personal relationship with a customer are a poor fit for a first agent.
Not every such process needs AI. Where data arrives in a fixed format, such as exports from your bank or online store, fixed rules that can be tested are enough. I only add AI where something has to read emails, attachments or other text without a fixed format.
When I assess which processes to automate, I check each one against four criteria. The more of them a process meets, the better a candidate it is:
- It repeats daily, weekly or monthly
- It follows rules you could write down on paper
- The data is already digital: in an email, a spreadsheet, a PDF or a system
- A mistake would cost money, and the result can be checked against the source
How I keep AI agents from making costly mistakes
I keep agents from making costly mistakes with fixed rules around the AI model: when an agent isn't sure or an input changes format, it stops and waits for a person.
In invoicing, this means that if a partner changes its report format, invoicing stops before a wrong invoice is created. The agent invoices only the items that clearly match, never calculates or estimates missing figures, and takes every value that drives the amount from a single source. A person then only has to check the exceptions and discrepancies the agent finds.
I built my own Python tool on the same principle: it works with Slovak public company registers and adds financial data and website addresses to about 2,000 company records. Its language model returns the data as structured output, in a fixed shape rather than free text, and a hard limit caps API spending. Every agent I build has these safeguards:
- Limits it must not cross, including a cap on AI spending
- Answers from the model in a fixed shape, not free text
- A log of every step, so you can trace what it did and when
- Human approval for steps where a mistake would cost money
- Fixed rules wherever the AI doesn't need to estimate anything
Calculator
What does work a system could do cost you?
Pick one task that keeps coming back, such as retyping documents, matching payments or putting reports together. The result is an estimate; we work out the real number in the consultation.
Estimate
26
hours a month
€4,680
a year for work a system could do
That is 3.3 working days every month.
Projects start at around €500; I price larger systems in parts. Once you accept the quote, I build the prototype for free.
Talk it through in a consultationWhich systems an AI agent can connect to
An AI agent can connect to most tools businesses commonly use: email, CRM, accounting software, an online store or shared spreadsheets. Where a system allows it, I connect through its API; otherwise I use file imports and exports or connect directly to the database of your own system. With accounting software, API access is often a paid add-on; Money S3, for example, offers it as an extension module. At the consultation we'll find out whether your system can be connected and whether you need to buy anything. We'll also agree in advance which data the agent may access.
I build agents in TypeScript and Node.js with the Vercel AI SDK, and I use Python for data-heavy jobs.
For companies in Slovakia, e-invoicing changes what an agent needs to read. From 1 January 2027, VAT payers established in Slovakia must, with some exceptions, issue invoices to Slovak businesses as structured XML files, which software can read directly with no AI extraction needed. AI still helps with documents that arrive as PDFs or scans, for example from foreign suppliers or from businesses that aren't VAT payers.
How much does an AI agent cost?
An agent for a single process starts at around €500. The price depends mainly on how many different formats the agent has to read, how many systems it writes to and how people approve exceptions: whether email is enough or you need a dedicated app. If an agent grows into a system your company runs on every day, it becomes custom software development: a project of several months that I price in parts.
Running costs for hosting and AI model calls range from tens to low hundreds of euros a month, depending on volume. By default I run the finished agent on my own accounts for a monthly fee, and a move to your own accounts can be arranged. I always fix its bugs for free; for the other terms, see how we work together.
After the first consultation, you get a quote split into parts, each with a specific price and timeline. If you approve it or some of its parts, I build a free prototype on a sample of your real documents or exports, so you can check that it will work before you make a final decision. For that, I need someone who knows the process and can tell me when the result is right. Automating a single process is then a few days of work. The full deployment with documentation and training usually takes 6 to 12 weeks, depending mainly on how many of your systems need to be connected. To start, use the form at the bottom of this page to tell me which process slows you down today.
Common questions
What's the difference between an AI agent and traditional automation?
Traditional automation does exactly what you tell it to and needs data in a fixed format. An AI agent can also handle input that has no fixed format, such as an email from a customer or a scanned document. In practice I combine the two: I use AI for the steps that involve reading text and attachments, and fixed rules that can be tested handle the rest.
When are n8n, Make or Zapier enough, and when do you need a custom AI agent?
Off-the-shelf tools like n8n, Make or Zapier are enough for a simple flow with fixed steps between common apps, for example when a completed form should create a spreadsheet row and an email to a colleague. A custom AI agent or automation is worth it when it has to read documents and emails with no fixed format, apply complex rules with exceptions, or work with your own system or database that has no ready-made connector. It also fits when you need a detailed log of every step and human approval for the important ones. If an off-the-shelf tool will do the job, I'll tell you at the consultation.
When is an internal AI assistant a better fit than an AI agent?
An internal AI assistant is the better fit when people in your company lose time searching for information in contracts and company procedures. An AI agent processes data and takes actions in your systems, for example entering an order. An AI assistant built on your own documents answers questions from what you already have in writing.
Where does our data go when an AI agent processes it?
Only to the systems and services we agree on in advance, including the language model provider. The agent gets access only to the data you choose, and it calls language models through paid business APIs, not through a chat app. If it processes personal data on my accounts, we sign a data processing agreement under Article 28 of the GDPR, in which I act as the processor and also list the hosting, database and language model provider. The AI knowledge assistant page explains how to keep both the data and its processing by the language model in the EU.
What's left for your people when an AI agent takes over a process?
Your people still check the exceptions, approve any step that involves money and make the decisions that call for judgment or a personal relationship with a customer. At the design stage, we decide together what the agent may do on its own and what a person has to approve.
Can I hire you just as an AI consultant, without any development work?
Yes, both a process audit and AI training for your team can be booked on their own. In the audit, we work out what's worth automating in your company. The first consultation is free, and you'll come away knowing whether automation would pay off for you, even if you decide not to go any further.
More services and projects
- Service Business process automation Business process automation for small and mid-sized companies: invoices, documents, quotes, orders, stock, attendance and reports. One process from €500.
- Service Document data extraction Invoice and receipt data extraction into Pohoda, Money and KROS, with checks on totals, VAT, duplicates and company IDs. A person reviews unclear cases.
- Service AI knowledge assistant An internal AI chatbot that answers staff questions from your contracts, procedures and meeting notes, with sources and access rights. Free prototype.
- Service AI training for teams AI training for employees on your team's real tasks, with a process audit and written AI rules. Run by a developer who taught IT at a vocational school.
Contact
Tell me what you still do by hand.
A few lines about the process that slows you down or the system you need are enough. Within eight hours I'll get back to you on whether and how it can be built, and if it makes sense, we'll set up a short call.
Prefer email or phone?
patrik.krajnak.dev@gmail.com +421 950 625 466
I reply within 8 hours. Based in Košice, Slovakia (CET), working remotely
Calls on Google Meet: Monday to Thursday 7:00 to 20:00, Friday until 18:00. Weekends by arrangement.
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