Field Limits

Values exceeding these limits are rejected with invalid_format.

Field	Limit
`operation_id`	128 characters
Reaction	32 characters
`phone`	E.164: `+` followed by 8–15 digits
Confirmation `code`	Digits only, `code_length` of them
`app_hash`	11 characters of the Base64 alphabet
`language`	BCP 47 tag, at most 35 characters
Push `token`	1–4096 characters
Address book changes	500 entries per request, `add` and `remove` together
Address book entry `name`	64 characters, single line
Address book size	5000 entries per device
Message `text`	4096 characters
Draft `text`	12288 characters
Mentions per text message or draft	32
Smileys per text message or draft	100
Installed smiley packs	100
File `name`	255 characters, no path separators
File `size`	1 byte–1 TiB
File `content_type`	Valid media type, at most 255 bytes, or empty
`nick`, `first_name`, `last_name`	64 characters, single line
`about`	1024 characters
`birthday`	`YYYY-MM-DD`, `--MM-DD` without the year, or empty
`gender`	`male`, `female` or empty
Custom status `emoji`	One emoji: up to 16 characters, none of them a letter, blank or control character
Custom status `text`	64 characters after trimming, single line
Custom status `until`	A moment in the future
Search `query`	2–64 characters
History `limit`	1–100 messages (default: 50)
Conversation `title`	1–100 characters after trimming
Conversation `description`	1000 characters
Initial `member_ids`	At most 100 entries
Invitation `expires_in`	60 seconds–30 days (default: 7 days, none when `permanent`)
Invitation `max_uses`	1–100 (default: 1 when addressed, none when shareable)
Invitation `name`	5–32 Latin letters, digits and underscores; a letter first, no underscore last; shareable invitations only
Moderation `reason`	500 characters
Ban/restriction duration	At most one year
Conversation `slow_mode_seconds`	0–86400 seconds

A single WebSocket message may not exceed 64 KB by default; the limit is configurable server-side.

Characters are Unicode code points. A text longer than a message holds is the client's to send as several messages, in order, each its own operation. Clients cut it alike, as a person would: at a blank line, else at a line break, else after a sentence, else at a space, looking only in the second half of what fits so that no message comes out much shorter than it could be, and where it stops fitting only when there is nowhere else; the blanks a cut falls on go with it, a mention is never cut, and a reply goes with the first message.