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Send a message to an existing chat

chats.messages.send(strchat_id, MessageSendParams**kwargs) -> MessageSendResponse
POST/v3/chats/{chatId}/messages

Send a message to an existing chat. Use this endpoint when you already have a chat ID and want to send additional messages to it.

Message Effects

You can add iMessage effects to make your messages more expressive. Effects are optional and can be either screen effects (full-screen animations) or bubble effects (message bubble animations).

Screen Effects: confetti, fireworks, lasers, sparkles, celebration, hearts, love, balloons, happy_birthday, echo, spotlight

Bubble Effects: slam, loud, gentle, invisible

Only one effect type can be applied per message.

Inline Text Decorations (iMessage only)

Use the text_decorations array on a text part to apply styling and animations to character ranges.

Each decoration specifies a range: [start, end) and exactly one of style or animation.

Styles: bold, italic, strikethrough, underline Animations: big, small, shake, nod, explode, ripple, bloom, jitter

{
  "type": "text",
  "value": "Hello world",
  "text_decorations": [
    { "range": [0, 5], "style": "bold" },
    { "range": [6, 11], "animation": "shake" }
  ]
}

Note: Style ranges (bold, italic, etc.) may overlap, but animation ranges must not overlap with other animations or styles. Text decorations only render for iMessage recipients. For SMS/RCS, text decorations are not applied.

ParametersExpand Collapse
chat_id: str
formatuuid

Message content container. Groups all message-related fields together, separating the โ€œwhatโ€ (message content) from the โ€œwhereโ€ (routing fields like from/to).

parts: List[Part]

Array of message parts. Each part can be text, media, or link. Parts are displayed in order. Text and media can be mixed freely, but a link part must be the only part in the message.

Rich Link Previews:

  • Use a link part to send a URL with a rich preview card
  • A link part must be the only part in the message
  • To send a URL as plain text (no preview), use a text part instead

Supported Media:

  • Images: .jpg, .jpeg, .png, .gif, .heic, .heif, .tif, .tiff, .bmp
  • Videos: .mp4, .mov, .m4v, .mpeg, .mpg, .3gp
  • Audio: .m4a, .mp3, .aac, .caf, .wav, .aiff, .amr
  • Documents: .pdf, .txt, .rtf, .csv, .doc, .docx, .xls, .xlsx, .ppt, .pptx, .pages, .numbers, .key, .epub, .zip, .html, .htm
  • Contact & Calendar: .vcf, .ics

Audio:

  • Audio files (.m4a, .mp3, .aac, .caf, .wav, .aiff, .amr) are fully supported as media parts
  • To send audio as an iMessage voice memo bubble (inline playback UI), use the dedicated /v3/chats/{chatId}/voicememo endpoint instead

Validation Rules:

  • A link part must be the only part in the message. It cannot be combined with text or media parts.
  • Consecutive text parts are not allowed. Text parts must be separated by media parts. For example, [text, text] is invalid, but [text, media, text] is valid.
  • Maximum of 100 parts total.
  • Media parts using a public url (downloaded by the server on send) are capped at 40. Parts using attachment_id or presigned URLs are exempt from this sub-limit. For bulk media sends exceeding 40 files, pre-upload via POST /v3/attachments and reference by attachment_id or download_url.
One of the following:
class TextPart: โ€ฆ
type: Literal["text"]

Indicates this is a text message part

value: str

The text content of the message. This value is sent as-is with no parsing or transformation โ€” Markdown syntax will be delivered as plain text. Use text_decorations to apply inline formatting and animations (iMessage only).

minLength1
maxLength10000
text_decorations: Optional[List[TextDecoration]]

Optional array of text decorations applied to character ranges in the value field (iMessage only).

Each decoration specifies a character range [start, end) and exactly one of style or animation.

Styles: bold, italic, strikethrough, underline Animations: big, small, shake, nod, explode, ripple, bloom, jitter

Style ranges may overlap (e.g. bold + italic on the same text), but animation ranges must not overlap with other animations or styles.

Characters are measured as UTF-16 code units. Most characters count as 1; some emoji count as 2.

Note: Text decorations only render for iMessage recipients. For SMS/RCS, text decorations are not applied.

range: List[int]

Character range [start, end) in the value string where the decoration applies. start is inclusive, end is exclusive. Characters are measured as UTF-16 code units. Most characters count as 1; some emoji count as 2.

animation: Optional[Literal["big", "small", "shake", 5 more]]

Animated text effect to apply. Mutually exclusive with style.

One of the following:
"big"
"small"
"shake"
"nod"
"explode"
"ripple"
"bloom"
"jitter"
style: Optional[Literal["bold", "italic", "strikethrough", "underline"]]

Text style to apply. Mutually exclusive with animation.

One of the following:
"bold"
"italic"
"strikethrough"
"underline"
class MediaPart: โ€ฆ
type: Literal["media"]

Indicates this is a media attachment part

attachment_id: Optional[str]

Reference to a file pre-uploaded via POST /v3/attachments (optional). The file is already stored, so sends using this ID skip the download step โ€” useful when sending the same file to many recipients.

Either url or attachment_id must be provided, but not both.

formatuuid
url: Optional[str]

Any publicly accessible HTTPS URL to the media file. The server downloads and sends the file automatically โ€” no pre-upload step required.

Size limit: 10MB maximum for URL-based downloads. For larger files (up to 100MB), use the pre-upload flow: POST /v3/attachments to get a presigned URL, upload directly, then reference by attachment_id.

Requirements:

  • URL must use HTTPS
  • File content must be a supported format (the server validates the actual file content)

Supported formats:

  • Images: .jpg, .jpeg, .png, .gif, .heic, .heif, .tif, .tiff, .bmp
  • Videos: .mp4, .mov, .m4v, .mpeg, .mpg, .3gp
  • Audio: .m4a, .mp3, .aac, .caf, .wav, .aiff, .amr
  • Documents: .pdf, .txt, .rtf, .csv, .doc, .docx, .xls, .xlsx, .ppt, .pptx, .pages, .numbers, .key, .epub, .zip, .html, .htm
  • Contact & Calendar: .vcf, .ics

Tip: Audio sent here appears as a regular file attachment. To send audio as an iMessage voice memo bubble (with inline playback), use /v3/chats/{chatId}/voicememo. For repeated sends of the same file, use attachment_id to avoid redundant downloads.

Either url or attachment_id must be provided, but not both.

formaturi
effect: Optional[MessageEffect]

iMessage effect to apply to this message (screen or bubble effect)

name: Optional[str]

Name of the effect. Common values:

  • Screen effects: confetti, fireworks, lasers, sparkles, celebration, hearts, love, balloons, happy_birthday, echo, spotlight
  • Bubble effects: slam, loud, gentle, invisible
type: Optional[Literal["screen", "bubble"]]

Type of effect

One of the following:
"screen"
"bubble"
idempotency_key: Optional[str]

Optional idempotency key for this message. Use this to prevent duplicate sends of the same message.

maxLength255
preferred_service: Optional[ServiceType]

Messaging service type

One of the following:
"iMessage"
"SMS"
"RCS"
reply_to: Optional[ReplyTo]

Reply to another message to create a threaded conversation

message_id: str

The ID of the message to reply to

formatuuid
part_index: Optional[int]

The specific message part to reply to (0-based index). Defaults to 0 (first part) if not provided. Use this when replying to a specific part of a multipart message.

formatint32
minimum0
ReturnsExpand Collapse
class MessageSendResponse: โ€ฆ

Response for sending a message to a chat

chat_id: str

Unique identifier of the chat this message was sent to

formatuuid
message: SentMessage

A message that was sent (used in CreateChat and SendMessage responses)

id: str

Message identifier (UUID)

formatuuid
created_at: datetime

When the message was created

formatdate-time
delivery_status: Literal["pending", "queued", "sent", 2 more]

Current delivery status of a message

One of the following:
"pending"
"queued"
"sent"
"delivered"
"failed"
is_read: bool

Whether the message has been read

parts: List[Part]

Message parts in order (text, media, and link)

One of the following:
class TextPartResponse: โ€ฆ

A text message part

reactions: Optional[List[Reaction]]

Reactions on this message part

handle: ChatHandle
id: str

Unique identifier for this handle

formatuuid
handle: str

Phone number (E.164) or email address of the participant

joined_at: datetime

When this participant joined the chat

formatdate-time
service: ServiceType

Messaging service type

One of the following:
"iMessage"
"SMS"
"RCS"
is_me: Optional[bool]

Whether this handle belongs to the sender (your phone number)

left_at: Optional[datetime]

When they left (if applicable)

formatdate-time
status: Optional[Literal["active", "left", "removed"]]

Participant status

One of the following:
"active"
"left"
"removed"
is_me: bool

Whether this reaction is from the current user

Type of reaction. Standard iMessage tapbacks are love, like, dislike, laugh, emphasize, question. Custom emoji reactions have type โ€œcustomโ€ with the actual emoji in the custom_emoji field. Sticker reactions have type โ€œstickerโ€ with sticker attachment details in the sticker field.

One of the following:
"love"
"like"
"dislike"
"laugh"
"emphasize"
"question"
"custom"
"sticker"
custom_emoji: Optional[str]

Custom emoji if type is โ€œcustomโ€, null otherwise

sticker: Optional[Sticker]

Sticker attachment details when reaction_type is โ€œstickerโ€. Null for non-sticker reactions.

file_name: Optional[str]

Filename of the sticker

height: Optional[int]

Sticker image height in pixels

mime_type: Optional[str]

MIME type of the sticker image

url: Optional[str]

Presigned URL for downloading the sticker image (expires in 1 hour).

formaturi
width: Optional[int]

Sticker image width in pixels

type: Literal["text"]

Indicates this is a text message part

value: str

The text content

text_decorations: Optional[List[TextDecoration]]

Text decorations applied to character ranges in the value

range: List[int]

Character range [start, end) in the value string where the decoration applies. start is inclusive, end is exclusive. Characters are measured as UTF-16 code units. Most characters count as 1; some emoji count as 2.

animation: Optional[Literal["big", "small", "shake", 5 more]]

Animated text effect to apply. Mutually exclusive with style.

One of the following:
"big"
"small"
"shake"
"nod"
"explode"
"ripple"
"bloom"
"jitter"
style: Optional[Literal["bold", "italic", "strikethrough", "underline"]]

Text style to apply. Mutually exclusive with animation.

One of the following:
"bold"
"italic"
"strikethrough"
"underline"
class MediaPartResponse: โ€ฆ

A media attachment part

id: str

Unique attachment identifier

formatuuid
filename: str

Original filename

mime_type: str

MIME type of the file

reactions: Optional[List[Reaction]]

Reactions on this message part

handle: ChatHandle
id: str

Unique identifier for this handle

formatuuid
handle: str

Phone number (E.164) or email address of the participant

joined_at: datetime

When this participant joined the chat

formatdate-time
service: ServiceType

Messaging service type

One of the following:
"iMessage"
"SMS"
"RCS"
is_me: Optional[bool]

Whether this handle belongs to the sender (your phone number)

left_at: Optional[datetime]

When they left (if applicable)

formatdate-time
status: Optional[Literal["active", "left", "removed"]]

Participant status

One of the following:
"active"
"left"
"removed"
is_me: bool

Whether this reaction is from the current user

Type of reaction. Standard iMessage tapbacks are love, like, dislike, laugh, emphasize, question. Custom emoji reactions have type โ€œcustomโ€ with the actual emoji in the custom_emoji field. Sticker reactions have type โ€œstickerโ€ with sticker attachment details in the sticker field.

One of the following:
"love"
"like"
"dislike"
"laugh"
"emphasize"
"question"
"custom"
"sticker"
custom_emoji: Optional[str]

Custom emoji if type is โ€œcustomโ€, null otherwise

sticker: Optional[Sticker]

Sticker attachment details when reaction_type is โ€œstickerโ€. Null for non-sticker reactions.

file_name: Optional[str]

Filename of the sticker

height: Optional[int]

Sticker image height in pixels

mime_type: Optional[str]

MIME type of the sticker image

url: Optional[str]

Presigned URL for downloading the sticker image (expires in 1 hour).

formaturi
width: Optional[int]

Sticker image width in pixels

size_bytes: int

File size in bytes

type: Literal["media"]

Indicates this is a media attachment part

url: str

Presigned URL for downloading the attachment (expires in 1 hour).

formaturi
handle: ChatHandle
id: str

Unique identifier for this handle

formatuuid
handle: str

Phone number (E.164) or email address of the participant

joined_at: datetime

When this participant joined the chat

formatdate-time
service: ServiceType

Messaging service type

One of the following:
"iMessage"
"SMS"
"RCS"
is_me: Optional[bool]

Whether this handle belongs to the sender (your phone number)

left_at: Optional[datetime]

When they left (if applicable)

formatdate-time
status: Optional[Literal["active", "left", "removed"]]

Participant status

One of the following:
"active"
"left"
"removed"
is_me: bool

Whether this reaction is from the current user

Type of reaction. Standard iMessage tapbacks are love, like, dislike, laugh, emphasize, question. Custom emoji reactions have type โ€œcustomโ€ with the actual emoji in the custom_emoji field. Sticker reactions have type โ€œstickerโ€ with sticker attachment details in the sticker field.

One of the following:
"love"
"like"
"dislike"
"laugh"
"emphasize"
"question"
"custom"
"sticker"
custom_emoji: Optional[str]

Custom emoji if type is โ€œcustomโ€, null otherwise

sticker: Optional[Sticker]

Sticker attachment details when reaction_type is โ€œstickerโ€. Null for non-sticker reactions.

file_name: Optional[str]

Filename of the sticker

height: Optional[int]

Sticker image height in pixels

mime_type: Optional[str]

MIME type of the sticker image

url: Optional[str]

Presigned URL for downloading the sticker image (expires in 1 hour).

formaturi
width: Optional[int]

Sticker image width in pixels

sent_at: Optional[datetime]

When the message was actually sent (null if still queued)

formatdate-time
delivered_at: Optional[datetime]

When the message was delivered

formatdate-time
effect: Optional[MessageEffect]

iMessage effect applied to a message (screen or bubble effect)

name: Optional[str]

Name of the effect. Common values:

  • Screen effects: confetti, fireworks, lasers, sparkles, celebration, hearts, love, balloons, happy_birthday, echo, spotlight
  • Bubble effects: slam, loud, gentle, invisible
type: Optional[Literal["screen", "bubble"]]

Type of effect

One of the following:
"screen"
"bubble"
from_handle: Optional[ChatHandle]

The sender of this message as a full handle object

id: str

Unique identifier for this handle

formatuuid
handle: str

Phone number (E.164) or email address of the participant

joined_at: datetime

When this participant joined the chat

formatdate-time
service: ServiceType

Messaging service type

One of the following:
"iMessage"
"SMS"
"RCS"
is_me: Optional[bool]

Whether this handle belongs to the sender (your phone number)

left_at: Optional[datetime]

When they left (if applicable)

formatdate-time
status: Optional[Literal["active", "left", "removed"]]

Participant status

One of the following:
"active"
"left"
"removed"
preferred_service: Optional[ServiceType]

Messaging service type

One of the following:
"iMessage"
"SMS"
"RCS"
reply_to: Optional[ReplyTo]

Indicates this message is a threaded reply to another message

message_id: str

The ID of the message to reply to

formatuuid
part_index: Optional[int]

The specific message part to reply to (0-based index). Defaults to 0 (first part) if not provided. Use this when replying to a specific part of a multipart message.

formatint32
minimum0
service: Optional[ServiceType]

Messaging service type

One of the following:
"iMessage"
"SMS"
"RCS"

Send a message to an existing chat

import os
from linq import LinqAPIV3

client = LinqAPIV3(
    api_key=os.environ.get("LINQ_API_V3_API_KEY"),  # This is the default and can be omitted
)
response = client.chats.messages.send(
    chat_id="550e8400-e29b-41d4-a716-446655440000",
    message={
        "parts": [{
            "type": "text",
            "value": "Hello, world!",
        }]
    },
)
print(response.chat_id)
{
  "chat_id": "550e8400-e29b-41d4-a716-446655440000",
  "message": {
    "id": "69a37c7d-af4f-4b5e-af42-e28e98ce873a",
    "created_at": "2025-10-23T13:07:55.019-05:00",
    "delivery_status": "pending",
    "is_read": false,
    "parts": [
      {
        "reactions": [
          {
            "handle": {
              "id": "69a37c7d-af4f-4b5e-af42-e28e98ce873a",
              "handle": "+15551234567",
              "joined_at": "2025-05-21T15:30:00.000-05:00",
              "service": "iMessage",
              "is_me": false,
              "left_at": "2019-12-27T18:11:19.117Z",
              "status": "active"
            },
            "is_me": false,
            "type": "love",
            "custom_emoji": null,
            "sticker": {
              "file_name": "sticker.png",
              "height": 420,
              "mime_type": "image/png",
              "url": "https://cdn.linqapp.com/attachments/a1b2c3d4/sticker.png?signature=...",
              "width": 420
            }
          }
        ],
        "type": "text",
        "value": "Hello!",
        "text_decorations": [
          {
            "range": [
              0,
              5
            ],
            "animation": "shake",
            "style": "bold"
          }
        ]
      }
    ],
    "sent_at": null,
    "delivered_at": null,
    "effect": {
      "name": "confetti",
      "type": "screen"
    },
    "from_handle": {
      "id": "550e8400-e29b-41d4-a716-446655440000",
      "handle": "+15551234567",
      "joined_at": "2025-05-21T15:30:00.000-05:00",
      "service": "iMessage",
      "is_me": false,
      "left_at": "2019-12-27T18:11:19.117Z",
      "status": "active"
    },
    "preferred_service": "iMessage",
    "reply_to": {
      "message_id": "550e8400-e29b-41d4-a716-446655440000",
      "part_index": 0
    },
    "service": "iMessage"
  }
}
{
  "error": {
    "status": 400,
    "code": 1002,
    "message": "Phone number must be in E.164 format"
  },
  "success": false
}
{
  "error": {
    "status": 401,
    "code": 2004,
    "message": "Unauthorized - missing or invalid authentication token"
  },
  "success": false
}
{
  "error": {
    "status": 404,
    "code": 2001,
    "message": "Resource not found"
  },
  "success": false
}
{
  "error": {
    "status": 500,
    "code": 3006,
    "message": "Internal server error"
  },
  "success": false
}
Returns Examples
{
  "chat_id": "550e8400-e29b-41d4-a716-446655440000",
  "message": {
    "id": "69a37c7d-af4f-4b5e-af42-e28e98ce873a",
    "created_at": "2025-10-23T13:07:55.019-05:00",
    "delivery_status": "pending",
    "is_read": false,
    "parts": [
      {
        "reactions": [
          {
            "handle": {
              "id": "69a37c7d-af4f-4b5e-af42-e28e98ce873a",
              "handle": "+15551234567",
              "joined_at": "2025-05-21T15:30:00.000-05:00",
              "service": "iMessage",
              "is_me": false,
              "left_at": "2019-12-27T18:11:19.117Z",
              "status": "active"
            },
            "is_me": false,
            "type": "love",
            "custom_emoji": null,
            "sticker": {
              "file_name": "sticker.png",
              "height": 420,
              "mime_type": "image/png",
              "url": "https://cdn.linqapp.com/attachments/a1b2c3d4/sticker.png?signature=...",
              "width": 420
            }
          }
        ],
        "type": "text",
        "value": "Hello!",
        "text_decorations": [
          {
            "range": [
              0,
              5
            ],
            "animation": "shake",
            "style": "bold"
          }
        ]
      }
    ],
    "sent_at": null,
    "delivered_at": null,
    "effect": {
      "name": "confetti",
      "type": "screen"
    },
    "from_handle": {
      "id": "550e8400-e29b-41d4-a716-446655440000",
      "handle": "+15551234567",
      "joined_at": "2025-05-21T15:30:00.000-05:00",
      "service": "iMessage",
      "is_me": false,
      "left_at": "2019-12-27T18:11:19.117Z",
      "status": "active"
    },
    "preferred_service": "iMessage",
    "reply_to": {
      "message_id": "550e8400-e29b-41d4-a716-446655440000",
      "part_index": 0
    },
    "service": "iMessage"
  }
}
{
  "error": {
    "status": 400,
    "code": 1002,
    "message": "Phone number must be in E.164 format"
  },
  "success": false
}
{
  "error": {
    "status": 401,
    "code": 2004,
    "message": "Unauthorized - missing or invalid authentication token"
  },
  "success": false
}
{
  "error": {
    "status": 404,
    "code": 2001,
    "message": "Resource not found"
  },
  "success": false
}
{
  "error": {
    "status": 500,
    "code": 3006,
    "message": "Internal server error"
  },
  "success": false
}