Permission bits

Permissions in a server are a 64-bit integer: each permission is one bit. A role holds a number, a bot is given a number when it is added to a server, and the permissions parameter of an install link is that number.

A member's permissions are the sum of the @everyone role and every role they hold. The owner of a server has all of them, and so does anyone with Administrator. In a channel, permissions are then adjusted by that channel's overwrites (first the category's, then the channel's own): a bit that an overwrite denies is taken away, one it allows is given. A member who cannot View channel can do nothing in it.

A permission marked channel can be allowed or denied for one channel; the others belong to the server as a whole.

Everyday

Name	Bit	Value	Where	What it allows
VIEW_CHANNEL	0	1	channel	See channels
SEND_MESSAGES	1	2	channel	Send messages
READ_HISTORY	2	4	channel	Read message history
ADD_REACTIONS	3	8	channel	Add reactions
MENTION_EVERYONE	4	16	channel	Mention @everyone
MANAGE_MESSAGES	5	32	channel	Manage messages
ATTACH_FILES	31	2147483648	channel	Attach files
EMBED_GAMES	32	4294967296	channel	Embed games
CREATE_INVITE	16	65536	channel	Create invites
CHANGE_NICKNAME	22	4194304	server	Change its own nickname

Voice

Name	Bit	Value	Where	What it allows
CONNECT	8	256	channel	Connect to voice
SPEAK	9	512	channel	Speak in voice
MUTE_MEMBERS	10	1024	channel	Mute members
MOVE_MEMBERS	11	2048	channel	Move members
STREAM	33	8589934592	channel	Go live
STREAM_REACT	34	17179869184	channel	React over a stream

Running the server

Name	Bit	Value	Where	What it allows
MANAGE_CHANNELS	17	131072	channel	Manage channels
MANAGE_ROLES	18	262144	server	Manage roles
MANAGE_SERVER	19	524288	server	Manage the server
KICK_MEMBERS	20	1048576	server	Kick members
BAN_MEMBERS	21	2097152	server	Ban members
MANAGE_NICKNAMES	23	8388608	server	Manage nicknames
MODERATE_MEMBERS	24	16777216	server	Put members in timeout
ADMINISTRATOR	30	1073741824	server	Administrator (everything, in every channel)

Rooms

Name	Bit	Value	Where	What it allows
CREATE_POSTS	35	34359738368	channel	Start forum posts
MANAGE_POSTS	36	68719476736	channel	Manage forum posts
TODO_ADD	37	137438953472	channel	Add to-do rows
TODO_CHECK	38	274877906944	channel	Tick to-do rows
TODO_EDIT	39	549755813888	channel	Edit others' to-do rows
TODO_MANAGE	40	1099511627776	channel	Manage to-do lists
DOC_EDIT	41	2199023255552	channel	Write in documents
DOC_MANAGE	42	4398046511104	channel	Manage documents
CREATE_POLLS	43	8796093022208	channel	Create polls
CREATE_GIVEAWAYS	44	17592186044416	channel	Create giveaways
EVENT_CREATE	45	35184372088832	channel	Create events
EVENT_MANAGE	46	70368744177664	channel	Manage events
PARTY_CREATE	47	140737488355328	channel	Create parties
PARTY_MANAGE	48	281474976710656	channel	Manage parties

Adding them up

To ask for View channels (1), Send messages (2) and Read message history (4), send 1 + 2 + 4 = 7. In code, add or | the values.

Values go up to 2⁴⁸, which is below 2⁵³, so an ordinary JavaScript number holds them exactly - but JavaScript's | and & operators work on 32 bits and silently cut higher bits off. Use BigInt for bit arithmetic:

Adding and checking permission bits

JavaScript

const VIEW_CHANNEL = 1n << 0n
const SEND_MESSAGES = 1n << 1n
const READ_HISTORY = 1n << 2n

const permissions = VIEW_CHANNEL | SEND_MESSAGES | READ_HISTORY   // 7n
const has = (held, flag) => (held & flag) === flag

console.log(permissions.toString())   // "7" - what goes in the install link

Python

VIEW_CHANNEL = 1 << 0
SEND_MESSAGES = 1 << 1
READ_HISTORY = 1 << 2

permissions = VIEW_CHANNEL | SEND_MESSAGES | READ_HISTORY   # 7

def has(held, flag):
    return held & flag == flag

print(str(permissions))   # "7" - what goes in the install link

Who may give what

A person can only give a role, or a bot, permissions they hold themselves; Administrator holds everything. A role can only be managed by someone whose highest role is above it. A bot's managed role is made just below the highest role of the person who added it.