Subscribe

Subscribe in the sidebar listens to any subject over core NATS. It needs no stream: you see what is published from the moment you subscribe, and nothing is stored. To read messages a stream already holds, use Messages or the live tail of that stream instead.

Start a subscription

1. Open Subscribe in the sidebar, or press Cmd+K and pick Go to Subscribe.
2. Type a subject and press Enter to add it. orders.* matches one token, orders.> everything below orders. Add as many subjects as you need; each one becomes a chip.
3. Click Start, or press Cmd+Enter (Ctrl+Enter on Windows and Linux).

Backspace in the empty field removes the last chip. Before you start, Quick add offers JetStream advisories, all JetStream events, everything (>), and subjects you subscribed to before. The subjects and recents are kept until you disconnect or switch to another connection.

NATS delivers every subject to >, but Natscope hides subjects that start with $ ($JS, $SYS, $KV, $SRV, …), _INBOX and the connection's own inbox prefix under a wildcard that doesn't name them. Subscribe to them by name, for example $JS.EVENT.>, to see them.

The feed

Messages show up newest first with their subject, time and a one-line preview of the payload: the decoded JSON when a subject mapping matches, the text otherwise. An arrow marks a message that waits for a reply. Click a message to open it in the same viewer as stream messages; the details close with the × in their corner.

A message that matches several of your subjects, such as orders.created under both orders.> and >, shows up once and is counted once. A plain NATS client with overlapping subscriptions would get one copy per subscription.

The line under the toolbar says how many messages arrived, how many the feed keeps, how many match the search, and how many were skipped. Next to it, a counter per subject; click one to show only that subject, or click its eye to mute it. Muted subjects stay out of the feed and the counters until you unmute them, and they do not use up the display rate. Muting or unmuting restarts the subscription, and messages published in that moment are missed, as core NATS keeps no copy.

• Search filters the received messages by subject and payload text.
• Pause freezes the feed; messages keep arriving in the background, and Resume shows how many wait. A very busy subject can outrun the pause buffer, which then keeps the latest ones.
• Clear empties the feed and the counters.
• Keep sets how many of the latest messages the feed holds, from 25 to 1,000.
• Display rate shows at most that many messages per second; the server skips the rest, does not queue them, and counts them as skipped. It applies to this subscription only, and changing it restarts the subscription.

Stop ends the subscription and keeps the messages on screen; Start listens again and adds to them.

A dot next to Subscribe in the sidebar shows that it is listening (amber while it reconnects). The subscription ends when you open another page, press Stop, disconnect, or switch to another connection; the messages stay on screen, and Start picks up from there.

Resend and reply

Resend in the viewer opens the message in a dialog where you can change the subject, payload and headers, and publishes it over core NATS. A JSON or text payload starts out byte for byte as it arrived; a Protobuf payload is shown as JSON and encoded again with its mapping. Nats-* headers, which the server manages, are left out. The feed keeps the first 64 KB of a message; a bigger one cannot be resent intact, so Resend is off for it.

A message published as a request carries a reply subject. Reply answers it: the dialog fills in the reply subject, and you write the payload. Only the first reply counts, and the requester waits only until its own timeout, so send the reply soon. Messages a JetStream push consumer delivers carry a $JS.ACK… reply subject; answering it would acknowledge the message, so Reply is off for them.

Permissions

If your NATS user may not subscribe to a subject, its chip shows a lock and no permission, and the other subjects keep working. A subject you may subscribe to still arrives when a wildcard covering it, such as orders.> over orders.created, is refused. When every subject is refused, the feed names the missing permissions. Publishing from Resend or Reply to a subject you may not publish to names the missing permission in the dialog.

When your permissions deny only part of a wildcard, for example secret.> under >, the server accepts the subscription and silently leaves the denied subjects out. Nothing tells Natscope about it, so those subjects don't show up.