PubNub API Limits

General API limits

All API requests, made either by the SDK or directly through the REST interface, can be throttled if Requests Per Second (RPS) exceed 25. This limit applies to every PubNub API. Contact PubNub Support if you need more than 25 requests per second.

These global limits apply alongside the feature‑specific limits below.

Keysets

Account Tier	Soft Limit	Hard Limit	If hard limited is exceeded?
Free	3	3	You can't exceed the limit. Limit of 3 keysets for Free tier accounts Effective February 3, 2025, all Free tier accounts will be limited to a maximum of three keysets. If your account exceeds this limit, you must delete existing keysets to create new ones.
Starter	unlimited	unlimited	n/a
Pro	unlimited	unlimited	n/a

Publish

Function	Soft Limit (Best Practices)	Hard Limit	If hard limited is exceeded
Publish Rate	Best practice: 10–15 messages/sec per channel. Publishing faster is possible. Slow subscribers may miss messages. Message buffer default: 100 messages per reconnect window (configurable). Multiplexing uses a single 100‑message buffer across channels. Example: 230 ms reconnect → ~400 msg/sec without loss. Example: 50 ms reconnect → ~2000 msg/sec. Larger buffers (300 or 500) help subscribers keep up. Consider buffer TTL. See Message Buffer Cache. If you wish to change the message queue limit, contact support@pubnub.com.	No throttling for keys in good standing (paid plan present or Free Tier within allowed limits). Use HTTP pipelining for higher throughput.	Free Tier accounts can upgrade for higher usage. For a first overage, we attempt to contact you before taking action. Error message (Channel quota exceeded)
# of users (publishers) per channel or keyset	Unlimited	N/A
Message Size	Less than < 30 KiB to be safe.	Length of GET request, including HTTP headers & URI encoding overhead (~32 KiB)	HTTP 400 error
Channel Name Length		2,048 characters
Channel ID Length		92 characters
User ID Length		92 characters
# of API keys per PubNub account?	An API is available if you need to manage an large number of keys (> 50). Contact us at support@pubnub.com if you need access to the Key Provisioning API.	Unlimited	N/A

Function	Soft Limit	Hard Limit	If hard limited is exceeded?
Subscribe Rate	Soft limit depends on subscriber constraints (buffer, round trips).	No limit Use HTTP Streaming for maximum throughput	N/A
# of Channels	Unlimited	N/A
# of Subscribers per channel or keyset	Unlimited	N/A
Message Buffer Cache	Size: 100 message queue. TTL: up to 16 minutes (can be shorter). If disconnect > 8–10 minutes, use Message Persistence. NOTE: Each socket has an in-memory message buffer (FIFO). It keeps the most recent 100 messages for 12–16 minutes. Publishing over 100 during reconnect can overflow the buffer and drop older messages. For long‑term retrieval, enable Message Persistence (up to 6 months or unlimited) and use its API.	Size: configurable on our end (may add costs). TTL: hard limit 20 minutes. Effective percent 90% → 18 minutes. Currently 80% → 16 minutes.	N/A
Catch-Up	100 messages (or size of buffer cache)	N/A
Channel Name Length		2,048 characters
# of Sockets/Instances per client	PubNub does not limit sockets/instances. Devices or platforms often limit TCP connections (some browsers allow ~40). Each PubNub client instance uses two TCP sockets: one for subscribes and one for non‑subscribe operations.	Unlimited	N/A
Multiplexing (available without Stream Controller)	10 to 50 channels When subscribing to many channels, channel groups allows for the persistence of channel lists.	No limit in client SDKs, but we advertise a hard limit of 100 channels. No server side limit, only limited by URI length of 32 KiB.
Channel Groups	Up to 10 channel groups, each with 100 channels for a total of 1,000 channels. You can change the limit of channels in the Admin Portal under your app's keyset configuration. Paid customers can increase the limit to up to 2,000 channels per channel group, for a total of 20,000 channels.	If subscribing to more than 10 channel groups, receive 400 HTTP status code with description Maximum channel registry count exceeded
Wildcard Subscribe	Depends on subscribe rate NOTE: refer to the note for Publish Rate	3 levels (2 dots) of wildcards: a. a.b. No limit to # of channels able to subscribe to in a wildcard subscribe. Wildcard Channel Names aren't allowed in Channel Groups.
Channel Group Name Length	92 Characters

Function	Soft Limit	If hard limited is exceeded?
File Size	5 MB	Contact us at support@pubnub.com to increase the file size limit.
File Retention	1, 3, 7, 15, or 30 days, or Unlimited

Presence

Function	Soft Limit	Hard Limit
Heartbeat	Minimum: 1 minute heartbeat & 29 second interval	Minimum: heartbeat:10; interval: 4 (lowest common denominator across 3.x SDKs; each have different hard limits) 4.x SDKs do not currently have limitations.
Presence Announce Max	100	We can adjust this limit, but there are considerations
Webhook Retries	Presence webhooks will try to POST to your URL endpoint for a maximum of 4 times, each with a 5s timeout; Ensure that the customer's server (REST endpoint) returns 200 NOTE: If a channel has reached the Presence Announce Max limit, we will not send webhook requests for that channel	If webhook has reached maximum number of retries, the request is lost.

Message Persistence

Function	Soft Limit	Hard Limit
Data Retention	1 day, 7 days, 30 days, 3 months, 6 months, 1 year, or Unlimited	7 days for Free tier customers
Maximum # of channels with message count	100 channels per a single API call	N/A

App Context

Item	Soft Limit	Notes
Size of a record	32 KiB	Maximum size of a user or channel metadata stored in the database, including custom fields.
Max user metadata records	1 million	Recommended maximum number of user metadata records using App Context API.
Max channel metadata records	1 million	Recommended maximum number of channel metadata records using App Context API.
Members added in a channel	5,000	Recommended maximum number of members per channel using App Context API.
Memberships per user	50,000	Recommended maximum number of memberships per user using App Context API.
Members per transaction request	20	Maximum number of members added or removed in a single call using App Context API.

Endpoint	Item	Hard Limit	Notes
Set user metadata	`name`	2,048 characters	Maximum length of the name asigned to the User ID.
Set user metadata	`externalId`	2,048 characters	Maximum length of the user's identifier in an external system that you want to refer to.
Set user metadata	`profileUrl`	2,048 characters	Maximum length of the URL to an image that can be used to visually represent the user.
Set user metadata	`email`	320 characters	Maximum length of the user' email address.
Set user metadata	`type`	50 characters	Maximum length of the tag that lets you categorize a user by their functional role. Limited to alphanumeric characters (0-9, a-z, A-Z) and the period/dot character (.).
Set user metadata	`status`	50 characters	Maximum length of the tag that lets you categorize a user by their current state. Limited to alphanumeric characters (0-9, a-z, A-Z) and the period/dot character (.).
Set user metadata	`custom`	`9007199254740991`	If you set `custom` fields with integer values, do not specify numbers larger than `9007199254740991` due to precision limitations in JSON implementations. For large integer values, for example PubNub timetoken values, use string values instead of integers.
Set channel metadata	`description`	2,048 characters	Maximum length of additional channel information.
Set channel metadata	`type`	50 characters	Maximum length of the tag that lets you categorize a channel by its functional role. Limited to alphanumeric characters (0-9, a-z, A-Z) and the period/dot character (.).
Set channel metadata	`status`	50 characters	Maximum length of the tag that lets you categorize a channel by its current state. Limited to alphanumeric characters (0-9, a-z, A-Z) and the period/dot character (.).
Set channel metadata	`custom`	`9007199254740991`	If you set `custom` fields with integer values, do not specify numbers larger than `9007199254740991` due to precision limitations in JSON implementations. For large integer values, for example PubNub timetoken values, use string values instead of integers.
Set channel membership metadata	`type`	50 characters	Maximum length of the tag that lets you categorize a membership by its functional role. Limited to alphanumeric characters (0-9, a-z, A-Z) and the period/dot character (.).
Set channel membership metadata	`status`	50 characters	Maximum length of the tag that lets you categorize a membership by its current state. Limited to alphanumeric characters (0-9, a-z, A-Z) and the period/dot character (.).
Set channel membership metadata	`custom`	`9007199254740991`	If you set `custom` fields with integer values, do not specify numbers larger than `9007199254740991` due to precision limitations in JSON implementations. For large integer values, for example PubNub timetoken values, use string values instead of integers.
Set channel members' metadata	`type`	50 characters	Maximum length of the tag that lets you categorize a channel member by their functional role. Limited to alphanumeric characters (0-9, a-z, A-Z) and the period/dot character (.).
Set channel members' metadata	`status`	50 characters	Maximum length of the tag that lets you categorize a channel member by their current state. Limited to alphanumeric characters (0-9, a-z, A-Z) and the period/dot character (.).
Set channel members' metadata	`custom`	`9007199254740991`	If you set `custom` fields with integer values, do not specify numbers larger than `9007199254740991` due to precision limitations in JSON implementations. For large integer values, for example PubNub timetoken values, use string values instead of integers.

Mobile push

Function	Soft Limit
# of Push Certificates	1 APNs certificate & 1 FCM key per PubNub Key Set
Push Notification Message Size	Maximum: 2 kB for APNs, 4 kB for FCM

Access Manager

Function	Soft Limit	Hard Limit
# of Tokens	No limits	N/A
Grant latency	Server to server (grant by server for server usage), give it 1 second between grant and usage Separate process (server grant, client usage), wait for grant callback before returning to client	N/A
Channels per grant	200	N/A

Functions

Activity	Soft Limit	Hard Limit
Number of Modules/Functions	10 modules per key	If you'd like a larger limit, contact support.
Number of Outbound Calls	10 requests per request type in a function execution (request types include PubNub API, `xhr`, and `KVStore` calls)	If you'd like a larger limit, contact support.
Rate Limit for Outbound Calls	100 total requests / second (include PubNub API, `xhr` and `KVStore` calls)	If you'd like a larger limit, contact support.
Execution Recursion Limit	Depth = 3, meaning how many recursions but also how many Function Types chaining	If you'd like a larger limit, contact support.
CPU Wall Time	10 seconds	If you'd like a larger limit, contact support.
KV Store Get Keys Limit for single call	100 Keys	If you'd like a larger limit, contact support.
KV Store Byte Size Limit for Keys	1KB	1KB
KV Store Byte Size Limit for Values	32KB	32KB
Max Interval for Interval Functions	1 hour	If you'd like a larger limit, contact support.
Number of console debug/error messages	250 messages	If you'd like a larger limit, contact support.

Events & Actions

Item	Free	Intro	Tier 1	Tier 2	Tier 3	Tier 4	Tier 5	Tier 6
Max events ingested	10K	2M	4M	25M	66M	200M	500M	Unlimited
Listeners	1	Unlimited	Unlimited	Unlimited	Unlimited	Unlimited	Unlimited	Unlimited
Actions per listener	1	3	3	3	3	3	Unlimited

General API limits​

Keysets​

Limit of 3 keysets for Free tier accounts

Publish​

Subscribe​

File sharing​

Presence​

Message Persistence​

App Context​

Mobile push​

Access Manager​

Functions​

Events & Actions​