Docs/Limits & Error Codes

Docs/Reference

Limits & Error Codes

System resource limits, edge rate limits, quotas, and protocol error codes reference.

Connection & Subscription Limits

Resource	Value	Behavior When Exceeded
Channels per Connection	50 channels	Subscription rejected with wire error `4300`. Socket remains open.
Channels per App	5000 channels	New subscriptions rejected with wire error `4300`. Resubscribes still succeed.
Heartbeat Interval	120 seconds	Client sends `pusher:ping` when idle; server responds with `pusher:pong`.
Hibernation State Size	16 KiB	Max state storage per hibernating socket. Closes with `4200` if exceeded.

Edge Rate Limiters

Rate limiting is enforced at Cloudflare Anycast edge locations:

Limiter	Threshold	Action When Exceeded
New Connection Limiter	500 handshakes / 10s per team	HTTP `429 Too Many Requests`
Channel Subscribe Limiter	20 subscriptions / 10s per socket	Wire event `pusher:error` (`4301`)
Client Event Limiter	50 client events / 10s per socket, 1000 / 10s per app	Wire event `pusher:error` (`4301`)

Concurrency Quotas (Socketo Cloud)

Plan	Concurrent Sockets	Action When Exceeded
Tier 1	1,000	WebSocket close code `4004` (Over quota)
Tier 2	3,000	WebSocket close code `4004` (Over quota)
Tier 3	5,000	WebSocket close code `4004` (Over quota)

Broadcast Billing (Socketo Cloud)

Plan	Monthly Fee	Included Broadcasts / Month	Overage
Tier 1	$9	2M	$1 per additional million
Tier 2	$20	12M	$1 per additional million
Tier 3	$36	30M	$1 per additional million

One event counts as one broadcast, no matter how many subscribers receive it. Subscriber fan-out is never billed separately.

Presence Channel Limits

Resource	Maximum Threshold	Action When Exceeded
Members per Presence Channel	100 unique user IDs	Subscription rejected with `4300`
Presence User ID Length	128 characters	Subscription rejected with `4300`
Presence User Object Size	1 KiB (1,024 bytes)	Subscription rejected with `4300`

Payload & Request Limits

Event Payload Size: Maximum 10 KiB (10,240 bytes) per event payload.
Batch Event Size: Maximum 10 events per POST /apps/:id/batch_events request.
Target Channels: Maximum 100 channels targeted in a single trigger request.

Protocol Feature Support Matrix

Feature	Support Status	Specification Reference
Public Channels	Supported	Pusher Protocol v7
Private Channels	Supported	HMAC-SHA256 authorization
Presence Channels	Supported	Roster awareness (max 100 members)
*Client Events (`client-`)**	Supported	Private & presence channels
User Sign-in (`pusher:signin`)	Supported	Connection-level identity `#server-to-user-<id>`
Direct User Events (`sendToUser`)	Supported	Dispatched to `pusher.user.bind()`
Outbound Webhooks	Supported	Occupancy, presence, and client events
*Encrypted Channels (`private-encrypted-`)**	Unsupported	End-to-end TweetNaCl encryption not implemented
*Cache Channels (`cache-`)**	Unsupported	Message caching on channel join not implemented
Watchlist Events (`pusher:watchlist`)	Unsupported	User status monitoring outside channels not implemented

Error Codes Reference

HTTP Status Codes

Code	Meaning
`400 Bad Request`	Malformed JSON payload or missing WebSocket upgrade headers.
`401 Unauthorized`	Invalid HMAC signature or timestamp expired (> 600s).
`403 Forbidden`	Application is disabled or suspended.
`404 Not Found`	Application ID not found or non-existent endpoint.
`429 Too Many Requests`	Edge rate limit threshold reached.

WebSocket Close Codes

Code	Reason
`4000`	Application requires SSL / TLS connection.
`4001`	Application key not found.
`4003`	Application is suspended or disabled.
`4004`	Application has exceeded concurrent connection quota.
`4006`	Invalid protocol version string format.
`4007`	Unsupported protocol version (expected `7`).
`4008`	No protocol version supplied in handshake query string.
`4009`	Connection unauthorized.
`4100`	Server over capacity; reconnect with exponential backoff.
`4200`	Reconnect immediately (also produced when user connection is terminated).
`4201`	Pong heartbeat not received within activity timeout.
`4202`	Closed after prolonged inactivity.

Wire Error Events (`pusher:error`)

Code	Meaning
`4009`	Channel authorization signature failed verification.
`4300`	Channel limit reached (presence roster full, channel name invalid, or payload exceeded).
`4301`	Socket rate limit exceeded (event flood or subscription flood).