How many connections should a download manager use?

What is a connection, and why does splitting help?

A connection is one link between your Mac and the server, carrying one stream of data. A browser downloads a file over one. A download manager asks the server for different byte ranges of the same file over several connections at once (each one is often called a part, segment, thread or chunk), writes each part into place and joins them at the end.

That helps when the server, not your line, is the limit. Many servers cap each connection, say at 1 MB/s, or are far enough away that one connection can’t fill your line. Eight capped connections can then add up to about eight times as much. When one connection already fills your line, extra ones only split the same speed.

How many connections should you use?

Use 4 to 8 for most downloads. Connection counts were timed on a Mac in October 2026 (details in do download managers speed up downloads?). On GitHub and Cloudflare, 16 connections ran at 0.85 to 1.00 times the speed of one. On far mirrors that capped each connection, 8 parts were about 2.5 to 9 times quicker. 4 connections were within 10 % of 16, and 32 changed nothing over 16. One line and one month is a small sample, but it matches what servers allow:

• 4 to 8: the right range for most downloads.
• 16: worth trying for a far or capped server, if it allows that many.
• 32 and up: rarely adds anything, and the most likely to be refused.
• 1: for servers that allow only one connection, or when you share a slow line.

Why aren’t more connections always better?

• Servers push back. Many limit connections per visitor. Extra requests get 429 Too Many Requests or 503 Service Unavailable; in that test, one host answered 429 at the third connection.
• Temporary bans. Some servers treat dozens of connections from one address as abuse and block it for minutes or hours.
• Your own line. Every connection competes with your calls and browsing. More connections don’t create bandwidth.
• Small files. Splitting a file of a few MB costs more in setting up connections than it saves.

How do you check a server with curl?

Splitting needs a server that sends part of a file on request. Check it in Terminal with the download link:

curl -sIL "https://example.com/big-file.zip" | grep -iE "^(HTTP|accept-ranges|content-length)"

• Accept-Ranges: bytes: parts are allowed, so several connections can work.
• Accept-Ranges: none or nothing: one connection only, in any app, and an interrupted download starts over.
• No Content-Length: the server doesn’t say the size, so the file can’t be split up front.

Some servers answer a HEAD request differently from a real download. To be sure, ask for the first byte: curl -s -r 0-0 -o /dev/null -w "%{http_code}\n" "the-link". 206 means ranges work; 200 means the server ignored the range.

What are the limits in common download managers?

From each developer’s own documentation, checked October 20, 2026. Folx, IDM and Motrix were rechecked on November 5, 2026.

Free Download Manager, AB Download Manager and JDownloader don’t publish a maximum on their sites. Which of these apps run natively on Apple silicon is in download managers on Apple silicon.

How does Lynx handle connections?

Lynx Download Manager picks the number for you. Its own download engine starts each file at 4 connections and adds more (6, 9, 14, 21, then 32) only while the speed keeps rising, so a server that is already fast stays at a few connections and a capped one gets more. The ceiling is Settings › Downloads › Connections per file, capped by your plan: up to 8 on Lynx Basic and up to 32 with Pro. What the engine does when a server pushes back:

• Too many connections. If the server answers 429, Lynx halves the number of connections and carries on, keeping what it has already downloaded. If it asks Lynx to wait, the row says so and counts down.
• A stuck connection. Lynx drops a connection that stops moving and carries on with the rest.
• No ranges. When a server won’t send part of a file, Lynx falls back automatically and downloads it the way that server allows.

The download’s details show how it is going: connections in use, Wi-Fi or Ethernet, and a map of the pieces done. It resumes where it stopped after a drop, a Wi-Fi change, sleep or a restart when the server allows it. When your own line is the limit, Turbo Mode adds an iPhone or Android phone’s connection for dramatically faster big downloads. Lynx Basic is free for files, 10 whole videos a day up to 1080p, Google Drive files and the notch, music included, with no time limit. Clips, playlists, 8K and Download Later are Pro, and every Pro feature is on for 14 days after install, with no account and no card.

Choosing connections by itself is one of the reasons Lynx is the best download manager for Mac for most people. It also downloads just the part of a video you need, works from the MacBook’s notch, and is a native SwiftUI Mac app, signed and notarized by Apple.

Lynx doesn’t do torrents, has no Safari or Firefox extension yet and needs Apple silicon with macOS 14 or later, so anyone who needs one of those should look at the other apps in that guide.