Guides
For tenants: how to show you can afford the rent without statements. For landlords: how to check a tenant and their certificate. Honest, with prices and sources.
By Tomasz Żyłka, Founder of CzynszOK and ClassKasa
For tenants
CzynszOK on your phone: add it to your home screen
How to add CzynszOK to the home screen on Android (Chrome) and iPhone (Safari), what you get then and how we check that it works on a phone.
· 3 min read
CzynszOK security checks: what runs on every change
Which automatic security checks CzynszOK runs on every code change, how each reacts to a finding and what the first Semgrep run turned up.
· 3 min read
ZAP: the free security scanner and 10 typical checks
What ZAP (Zed Attack Proxy) is, how a baseline scan differs from an active one, and ten typical checks you see in its reports. An explainer for the curious.
· 4 min read
How to prove income to a landlord without statements
How to prove income to a landlord without statements or showing your salary: what the landlord really wants, your options and what works in a few minutes.
· 8 min read
Tenant certificate: what it is and how to get one fast
What a tenant certificate is, the three kinds, what a landlord sees and how to get one in minutes from your bank data, with no documents and no analyst.
· 8 min read
For landlords
Can the tenant afford the rent? How to check it
How a landlord judges if a tenant can afford the rent: rules of thumb, weak documents, what a bank-based Rent X zł: OK means, couples, deposit.
· 8 min read
How to check a tenant before signing a lease
What a landlord in Poland may lawfully check about a tenant: identity, income, rent history, debt registers. Prices and times of the services, a ready message.
· 8 min read
How to check a tenant certificate: a landlord guide
How a landlord in Poland checks a CzynszOK tenant certificate: scan the QR or type the code at czynszok.pl/en/v, what each status means, what to compare.
· 7 min read
Tenant check without BIK: what shows how you pay rent
Tenant check without BIK: what the registers show, what a query costs, what your account history says about paying rent, and how to combine the two.
· 7 min read
How we count, and the comparison
Smart read: how we count income from two banks
How CzynszOK counts income across two banks and four accounts: own and partner transfers once, currencies at the NBP rate, the deposit. Eight rules.
· 8 min read
Tenant verification in Poland 2026: an honest comparison
Tenant screening in Poland compared: simpl.rent, Zaufany Lokator, plokey, Rendin, BIK and KRD reports, documents and CzynszOK. Price, when you pay, data, speed.
· 19 min read