Packet SenderReplayTestingTCPUDPComparisonAlternatives
Packet Sender Alternative with TLS, DTLS and STARTTLS (and a Proxy)
Packet Sender sends TCP, UDP and SSL packets. InterceptSuite adds a MITM proxy so you can capture real traffic, then edit and replay it over TCP, TLS, DTLS, QUIC and STARTTLS.
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InterceptSuite Team
October 6, 2026·5 min read
Short answer: Packet Sender is a free, open-source tool for sending and receiving TCP, UDP and SSL packets, with built-in servers. It is excellent for poking a server you control. InterceptSuite starts from the other end: it sits between a real application and the network, captures the genuine traffic, and then lets you edit and replay it. Replay also works on its own: enter a host, port and protocol and send anything you like, including over DTLS, QUIC and mid-session STARTTLS.
Last updated 6 October 2026.
Side by side
| Packet Sender | InterceptSuite | |
|---|---|---|
| Price | Free, open source | Paid, 7-day trial |
| Sends TCP, UDP, SSL | Yes | Yes, through Replay |
| DTLS | Built-in DTLS server | DTLS client and interception |
| QUIC | Not listed | QUIC v1, with stream and ALPN controls |
| STARTTLS mid-session | Not supported | Send plain commands, then click Upgrade TLS |
| Capture real app traffic | No, it is not a proxy | Yes, SOCKS5 MITM with Proxy History |
| Build a packet from scratch (host, port, protocol, payload) | Yes | Yes, in the Replay tab |
| Send from captured traffic | No | Right-click a packet, Send to Replay |
| Built-in servers and scheduling | Yes | No |
Other TCP/UDP GUI tools people use
- Hercules SETUP utility is a free terminal for TCP and UDP on Windows. Its publisher's download page lists version 3.2.8 from 2014.
- SocketTest is a Java TCP client and server. Its SourceForge project was last updated in 2013.
- netcat and openssl s_client are command-line tools for plain and TLS connections.
All of these work for a simple connect, send and read. The gaps for current work are TLS options such as ALPN, DTLS and QUIC, STARTTLS upgrades and hex editing in one place.
When Packet Sender is the right tool
- You want to send a hand-built packet to a server and read the reply.
- You need a quick TCP, UDP or SSL listener to test a client against.
- You want something free that runs on many platforms.
When InterceptSuite fits better
- You do not know the exact bytes yet. Capture them from the real client first, then edit.
- The service upgrades to TLS. Replay's STARTTLS flow is built for SMTP, IMAP and PostgreSQL-style handshakes.
- You test DTLS or QUIC devices. Send datagrams or streams with the right ALPN and see the replies.
- You want to compare variations. Use one tab per test and keep the sessions with the project.
Learn the workflow in Manually Test STARTTLS with Replay or read the Replay overview.
What Replay is not for
Replay is for protocol testing, not load generation. Use dedicated tools for flooding or stress tests.