The short answer
To check whether a project is RERA-registered, search the project name, the promoter's name or the registration number on the official UP-RERA portal at up-rera.in. For projects in Noida, Greater Noida and along the Yamuna Expressway, the same register is searchable on this site, one page per registered project, and what you read here is worth verifying against the official portal before you act.
Why it matters
In Uttar Pradesh, a promoter cannot legally advertise, sell or take money for a project that is not registered with UP-RERA. A valid registration number is the floor, not the ceiling: it means the project is on the regulator's record, its plans and completion date are filed, and buyer money must run through a monitored account.
The number to ask for
Every registered project has a registration number in the form UPRERAPRJ followed by digits (a project that has only applied carries a promoter number, UPRERAPRM). Ask for it in writing. Then look it up: on the official portal at up-rera.in, or on this site, where every registered project in Noida, Greater Noida and the Yamuna Expressway has its own page under its number.
What a valid registration proves
That the project exists on the record, with a declared completion date, a promoter, filed plans and a collection account. It does not prove the project is on time, that the promoter has a clean record, or that the completion date has not already moved. Those are separate reads, and they are exactly what the register also shows.
What to read next
Once you have confirmed the registration, read three things: whether the completion date on file matches what you were told, how the promoter's other projects have run, and how many complaints are on record. All three are on the register, and all three are on the project's page here.
Checking the promoter itself is worth a minute too. Eldeco's La Vida Bella, in Sector 12, Greater Noida West, is filed to a different Eldeco entity than its sibling projects elsewhere in the district, and its own promoter-and-approvals page sets out how to check that entity's CIN and layout approval directly against the filing.
Where to look it up
Start with the official portal, up-rera.in. For a faster read of the Gautam Buddha Nagar register, browse every registered project here by area, delay or registration date.
Reading a specific project?
Talk to an advisor who takes you through its filings, before any decision.