FileZilla is a file-transfer client that moves files and directories between a computer and a remote server. It places the local filesystem on the left and the server filesystem on the right, then sends dragged or selected items through a transfer queue. FileZilla speaks FTP and its encrypted variants, and it can connect through SFTP when the server uses SSH. It changes files only when the user uploads, downloads, renames, deletes, or moves them; opening a connection alone does not synchronize the two locations.
Local and remote panes
The paired panes resemble a file manager, but they refer to different machines. A path above the left tree identifies the computer’s folder. The path above the right tree identifies the current directory on the server. Double-clicking a local file starts an upload, while double-clicking a remote file starts a download. Directories and multi-file selections use the context menu or drag and drop.
Question marks beside unopened remote directories do not mean that the folders are broken. FileZilla cannot know whether they contain subdirectories until it requests that directory from the server. The message log records those requests and the server’s replies, which helps separate a permission error from a path typed incorrectly.
Quickconnect forgets details
Quickconnect is meant for a temporary test. The fields accept a host, username, password, and optional port. An SFTP or FTPS connection needs its protocol in the host field when the address alone does not identify it. FileZilla remembers only the ten most recent Quickconnect entries, and that list cannot be edited.
Site Manager is the persistent route. It keeps the protocol, logon method, directories, transfer settings, and other site-specific choices under a named entry. A working temporary connection can move into Site Manager through Copy current connection to Site Manager. This avoids retyping credentials and prevents an FTP default from replacing an intended SFTP connection during a later visit.
The queue has rules
FileZilla sends double-clicked and dragged items to the transfer queue. Add to Queue holds them without starting, while the toolbar starts the waiting work later. Separate FTP sessions handle directory browsing and file data, so the remote pane normally remains usable while several transfers continue.
Some servers restrict the number of sessions from one address and answer with a 421 Too many connections error. A Site Manager entry can limit simultaneous connections for that server. Setting the limit to one solves the server restriction, but it also prevents browsing while a file transfer occupies the only session.
Filters change uploads
Directory Comparison colors differences according to file size or modification time. It does not inspect file contents, and it depends on the local and remote roots representing the same directory structure. Synchronized Browsing also requires matching default roots in Site Manager; otherwise navigation on one side cannot reliably mirror the other.
Filename filters hide matching entries from listings and affect directory transfers. When a filter hides a file inside an uploaded folder, FileZilla leaves that file out of the queue. A directory can therefore appear to transfer successfully while excluded build artifacts or hidden files never reach the server. Reviewing active filters matters before treating the remote tree as a complete copy.
Conflicts need a choice
If a target name already exists, FileZilla normally asks whether to overwrite, rename, skip, or apply a decision to more items. Overwrite replaces the remote or local file selected by the transfer direction; it does not merge their contents. Modification times can also differ because server clocks and transfer settings affect them. The failed and successful queue tabs retain outcomes after the active queue empties, so a finished progress bar alone does not prove that every selected item arrived.
