Apollo Download ManagerApollo Download Manager
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Protocols and limits

What Apollo Download Manager downloads, and what it can do for each kind of link. The tables below are checked against what Apollo Download Manager's download engine reports about itself, so they change only when the engine does (crates/velocity-transfer/tests/user_guide.rs).

Direct downloads

ProtocolLinksSeveral connectionsResumesResume checked against the fileHTTP/2Encrypted
HTTP and HTTPShttp://, https://YesYesYesYesYes
FTP and FTPSftp://, ftps://NoYesYesNoYes
SFTPsftp://NoYesYesNoYes

What the columns mean:

  • Several connections: Apollo Download Manager splits the file and downloads its parts over several connections at once. It starts with all the connections a download may use (8 by default) and keeps only those that make it faster. FTP and SFTP use one connection per download for now.

  • Resumes: a paused download, or one interrupted by a restart, a crash or a power cut, goes on from the last progress Apollo Download Manager saved, not from the start.

  • Resume checked against the file: before resuming, Apollo Download Manager checks the file on the server is still the same one (its ETag or modification time). If it changed, Apollo Download Manager starts over rather than mix two versions.

  • HTTP/2: with a server that speaks HTTP/2, several parts share one connection. Apollo Download Manager tries separate connections too, and keeps whichever is faster.

  • Encrypted:

    • HTTPS: always, and the server's certificate is always checked. There is no way to turn that check off.

    • FTP: an ftps:// link is encrypted. A plain ftp:// link is encrypted only when you tick "Require encryption (FTPS)" when adding it. Without that, the Add dialog warns that the login and the file can be read on the network.

    • SFTP: always. The first time you download from a server, Apollo Download Manager asks you to confirm the server's identity (Downloads).

Limits that apply to every direct download:

  • Redirects are followed only to http:// and https:// links, at most 10. A redirect from https:// to http:// stops and asks first (Troubleshooting).

  • No proxy or .netrc from the system: Apollo Download Manager uses only the proxy set in its own Settings (Settings).

  • Checksums: when you give one (MD5, SHA-1, SHA-224, SHA-256, SHA-384 or SHA-512), the finished file is checked against it, and the download is marked verified.

FeatureSupported
Metalink filesYes

A Metalink file lists one or more files, with their mirrors and checksums. When the Metalink switch is on (Settings, Advanced; off by default, as in V1), a link to a .metalink or .meta4 file adds the files it describes, and Apollo Download Manager downloads each from its mirrors and checks it against the checksums the Metalink file gives.

A Metalink file on your computer: in the Add dialog, Choose Metalink files… adds every file each one lists, in the folder you choose, or the default one (#222).

BitTorrent

Torrents and magnet links are downloaded by a separate program, the torrent helper, which uses libtorrent. It supports BitTorrent v1, v2 and hybrid torrents, magnet links, DHT, peer exchange, choosing files, and seeding. The Torrents guide covers them. Unlike the table above, this part isn't checked against the engine automatically.

Not supported

  • Other links, such as file://, data: or scp://, are refused in the Add dialog, with the reason.

  • Several connections for FTP and SFTP: each downloads over one connection for now.

  • An HTTPS proxy for SFTP and torrents: choose an HTTP or SOCKS5 proxy for those (Settings).