Answers before you
even ask

MergeQaiPro places two versions of a file side by side and marks every deviation in colour — line by line, and within a line even character by character. Whatever you see can be moved from one side to the other with a single click. Besides text, the program also compares folders, images and any file byte by byte; for merges from two directions there is the three-way comparison.

For anyone who has to hold two states of a file or folder against each other: developers, administrators, translators, editors, photographers — and everyone who wants to know what changed between two backups. Knowledge of regular expressions is explicitly not required.

Three things you won't find elsewhere:

• Regex without regex knowledge: hide timestamps, numbers or GUIDs using ready-made building blocks — with a live preview on real lines from your file.
• Moved-block detection: reordered blocks get a colour of their own instead of being reported twice as “deleted” and “inserted”.
• Renamed folders are paired by their content, not by their name.

Windows 10 / 11 (64-bit). Other platforms are not planned at present.

Yes. No trial period, no locked features, no file limit and no credit card. MergeQaiPro is our entry-level product and stays free.

Registering with your e-mail address is what the product is worth to us: it lets us tell you about new versions. It takes less than a minute and requires no payment details. You can unsubscribe from the new-version notification at any time with a single click — the link is in every one of those e-mails.

No. Both belong to our paid products. MergeQaiPro runs after downloading, without activation.

No. You will only receive notices about new program versions — and only for as long as you haven't objected.

Download the file from the product page and start it. On start-up the splash screen appears briefly, then the main window opens with the start page and its three tiles for file, folder and three-way comparison.

No, this is not a virus warning. It appears for every new application whose code-signing certificate has not yet built up reputation with Microsoft. Click “More info” and then “Run anyway”. The product page shows the file's SHA-256 fingerprint so you can verify it independently.

Compute the checksum in PowerShell with Get-FileHash <path-to-file> -Algorithm SHA256 and compare the result with the SHA-256 value on the product page. Identical values mean the file is intact.

With the regex building blocks. You click the pattern together from ready-made pieces — timestamps, numbers, version numbers, GUIDs, IP and e-mail addresses, web addresses, Windows paths, comments. Every rule immediately shows what it matches on real lines from your file. If an expression is invalid, the program states the reason in ordinary language rather than as a parser error.

You decide, via the filter bar. The main switch “Only real differences” treats pure formatting as identical. Individually switchable are whitespace, indentation, line endings, letter case, blank lines and special characters, among others.

Yes. When a block is sorted to a different place, an ordinary comparison raises the alarm twice: red for “deleted”, green for “inserted” — although nothing changed in substance. MergeQaiPro recognises such moves and colours them turquoise.

Project_2025 becomes Project_2026 — to a name-based comparison these are two different directories. MergeQaiPro pairs them by their content and treats them as the same one: a single row carrying both names, with the real differences below it.

Yes, in four display modes: side by side, overlay (with an opacity slider), slider (with a draggable divider) and difference (with an amplification slider). Zoom and panning can be coupled. On top of that comes a similarity rating in per cent that weighs structure, brightness, colour and frequency content — it recognises two versions of the same photo at different compression levels as practically identical.

Two edits of the same original in three columns: Left · Base · Right. You see who changed what — and where both touched the same spot.

Then the byte-by-byte comparison takes over, as a hex view with differing bytes highlighted. If the files are identical, the program tells you so directly.

No. MergeQaiPro works entirely locally on your machine. Your files never leave the PC.

Blocks you take over initially land in the view only — saving happens on your instruction. If you close a comparison with unsaved changes, the program asks first. When copying in the folder comparison, you are likewise asked before an existing file would be overwritten.

Not personal support. The product is free and therefore carries no ticket promise — we would rather say so up front than keep you waiting. The manual makes up for it: twelve chapters from the first steps to every keyboard shortcut, illustrated throughout. Personal contact with the developer belongs to SynQaiPro and MuSéa.

Yes. We inform you about new versions by e-mail, provided you are registered and have not objected.

In the user manual. It explains every window and every switch step by step and is illustrated throughout.