The developer with a client to test
You're writing something that speaks a socket — game netcode, an embedded client, a custom line protocol, your first `connect()`. You need to know it sends what you think and handles what comes back.
- Point your client at the ECHO or MOCK API preset and read every request/response in the stream
- Flip to hex to confirm the exact bytes and framing
- Script canned replies so the server behaves like the real backend before it exists
- Broadcast or direct-send to poke your client's receive path
The instructor teaching the wire
A room needs to see what a socket does. Slides don't move; this does — connections appear, counters climb, messages scroll, a kick drops a client on cue.
- Load the CHAT RELAY preset and have the class connect and talk through it
- Record a session, then replay it next lecture at any speed
- Show framing live: switch newline → length-prefix and watch parsing change
- Pair with Pcapsule to jump from "what the server saw" to "what the packet looked like"
The lab & CTF builder
You need a throwaway service that stands in for something — a listener, a status endpoint, a chatty device — logs what reaches it, and answers on script.
- Use the auto-responder to turn any line into a scripted, templated reply
- GEO MAP preset streams live markers — a ready-made moving data source
- Delay, broadcast, or hang-up rules to shape the exercise
- Export the session as JSONL and ship it with the challenge
The bench & QA engineer
A device is on the bench and you need to see what it emits and feed it what it expects — the job Hercules did, now cross-platform with UDP, hex and scripting.
- BINARY DEVICE preset: length-prefixed frames, hex in and hex out
- IOT SENSOR preset: a telemetry feed plus
READ/STATUSresponders, over TCP and UDP - Per-client byte counters to confirm what actually went out
- Token auth to mimic a gated device handshake
The preset map
Pick the one closest to your job
| Preset | Sets up | Reach for it when |
|---|---|---|
| Echo chamber | TCP, newline, echo + commands | first sanity check of any client |
| Chat relay | rebroadcasts every line to all | a classroom or multi-client demo |
| IoT sensor | TCP+UDP, telemetry feed, READ/STATUS rules | a device client or telemetry consumer |
| Mock API | regex-routed replies, delay, hang-up | standing in for a line-based backend |
| Binary device | length-prefix framing, hex replies | binary protocols and hex practice |
| Geo map | the built-in moving-marker feed | a live data source / the FTXUI map |
| Gated | require /auth <token> | testing an authenticated handshake |
Not sure it fits your case? If a client connects over TCP or UDP, you can watch it and script its other end here.// and if you need the packet-level view, that's Pcapsule's job