diff --git a/CHANGELOG.md b/CHANGELOG.md
index 6aeb4ba2..6859b09c 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -11,6 +11,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### New features
 
+* Added `ChatDeepSeek()` for chatting via [DeepSeek](https://www.deepseek.com/). 
 * Added `ChatHuggingFace()` for chatting via [Hugging Face](https://huggingface.co/). (#144)
 * Added `ChatPortkey()` for chatting via [Portkey AI](https://portkey.ai/). (#143)
 
diff --git a/chatlas/__init__.py b/chatlas/__init__.py
index 133fd13c..9266cfa5 100644
--- a/chatlas/__init__.py
+++ b/chatlas/__init__.py
@@ -8,6 +8,7 @@
 from ._provider import Provider
 from ._provider_anthropic import ChatAnthropic, ChatBedrockAnthropic
 from ._provider_databricks import ChatDatabricks
+from ._provider_deepseek import ChatDeepSeek
 from ._provider_github import ChatGithub
 from ._provider_google import ChatGoogle, ChatVertex
 from ._provider_groq import ChatGroq
@@ -31,6 +32,7 @@
     "ChatAuto",
     "ChatBedrockAnthropic",
     "ChatDatabricks",
+    "ChatDeepSeek",
     "ChatGithub",
     "ChatGoogle",
     "ChatGroq",
diff --git a/chatlas/_provider_deepseek.py b/chatlas/_provider_deepseek.py
new file mode 100644
index 00000000..b60f34d8
--- /dev/null
+++ b/chatlas/_provider_deepseek.py
@@ -0,0 +1,171 @@
+from __future__ import annotations
+
+import os
+from typing import TYPE_CHECKING, Optional, cast
+
+from ._chat import Chat
+from ._logging import log_model_default
+from ._provider_openai import OpenAIProvider
+from ._turn import Turn
+from ._utils import MISSING, MISSING_TYPE, is_testing
+
+if TYPE_CHECKING:
+    from openai.types.chat import ChatCompletion, ChatCompletionMessageParam
+
+    from .types.openai import ChatClientArgs, SubmitInputArgs
+
+
+def ChatDeepSeek(
+    *,
+    system_prompt: Optional[str] = None,
+    model: Optional[str] = None,
+    api_key: Optional[str] = None,
+    base_url: str = "https://api.deepseek.com",
+    seed: Optional[int] | MISSING_TYPE = MISSING,
+    kwargs: Optional["ChatClientArgs"] = None,
+) -> Chat["SubmitInputArgs", ChatCompletion]:
+    """
+    Chat with a model hosted on DeepSeek.
+
+    DeepSeek is a platform for AI inference with competitive pricing
+    and performance.
+
+    Prerequisites
+    -------------
+
+    ::: {.callout-note}
+    ## API key
+
+    Sign up at <https://platform.deepseek.com> to get an API key.
+    :::
+
+    Examples
+    --------
+
+    ```python
+    import os
+    from chatlas import ChatDeepSeek
+
+    chat = ChatDeepSeek(api_key=os.getenv("DEEPSEEK_API_KEY"))
+    chat.chat("What is the capital of France?")
+    ```
+
+    Known limitations
+    --------------
+
+    * Structured data extraction is not supported.
+    * Images are not supported.
+
+    Parameters
+    ----------
+    system_prompt
+        A system prompt to set the behavior of the assistant.
+    model
+        The model to use for the chat. The default, None, will pick a reasonable
+        default, and warn you about it. We strongly recommend explicitly choosing
+        a model for all but the most casual use.
+    api_key
+        The API key to use for authentication. You generally should not supply
+        this directly, but instead set the `DEEPSEEK_API_KEY` environment variable.
+    base_url
+        The base URL to the endpoint; the default uses DeepSeek's API.
+    seed
+        Optional integer seed that DeepSeek uses to try and make output more
+        reproducible.
+    kwargs
+        Additional arguments to pass to the `openai.OpenAI()` client constructor.
+
+    Returns
+    -------
+    Chat
+        A chat object that retains the state of the conversation.
+
+    Note
+    ----
+    This function is a lightweight wrapper around [](`~chatlas.ChatOpenAI`) with
+    the defaults tweaked for DeepSeek.
+
+    Note
+    ----
+    Pasting an API key into a chat constructor (e.g., `ChatDeepSeek(api_key="...")`)
+    is the simplest way to get started, and is fine for interactive use, but is
+    problematic for code that may be shared with others.
+
+    Instead, consider using environment variables or a configuration file to manage
+    your credentials. One popular way to manage credentials is to use a `.env` file
+    to store your credentials, and then use the `python-dotenv` package to load them
+    into your environment.
+
+    ```shell
+    pip install python-dotenv
+    ```
+
+    ```shell
+    # .env
+    DEEPSEEK_API_KEY=...
+    ```
+
+    ```python
+    from chatlas import ChatDeepSeek
+    from dotenv import load_dotenv
+
+    load_dotenv()
+    chat = ChatDeepSeek()
+    chat.console()
+    ```
+
+    Another, more general, solution is to load your environment variables into the shell
+    before starting Python (maybe in a `.bashrc`, `.zshrc`, etc. file):
+
+    ```shell
+    export DEEPSEEK_API_KEY=...
+    ```
+    """
+    if model is None:
+        model = log_model_default("deepseek-chat")
+
+    if api_key is None:
+        api_key = os.getenv("DEEPSEEK_API_KEY")
+
+    if isinstance(seed, MISSING_TYPE):
+        seed = 1014 if is_testing() else None
+
+    return Chat(
+        provider=DeepSeekProvider(
+            api_key=api_key,
+            model=model,
+            base_url=base_url,
+            seed=seed,
+            name="DeepSeek",
+            kwargs=kwargs,
+        ),
+        system_prompt=system_prompt,
+    )
+
+
+class DeepSeekProvider(OpenAIProvider):
+    @staticmethod
+    def _as_message_param(turns: list[Turn]) -> list["ChatCompletionMessageParam"]:
+        from openai.types.chat import (
+            ChatCompletionAssistantMessageParam,
+            ChatCompletionUserMessageParam,
+        )
+
+        params = OpenAIProvider._as_message_param(turns)
+
+        # Content must be a string
+        for i, param in enumerate(params):
+            if param["role"] in ["assistant", "user"]:
+                param = cast(
+                    ChatCompletionAssistantMessageParam
+                    | ChatCompletionUserMessageParam,
+                    param,
+                )
+                contents = param.get("content", None)
+                if not isinstance(contents, list):
+                    continue
+                params[i]["content"] = "".join(
+                    content.get("text", "") for content in contents
+                )
+
+        return params
diff --git a/docs/_quarto.yml b/docs/_quarto.yml
index 2c7bc351..6a0656ae 100644
--- a/docs/_quarto.yml
+++ b/docs/_quarto.yml
@@ -117,6 +117,7 @@ quartodoc:
         - ChatAzureOpenAI
         - ChatBedrockAnthropic
         - ChatDatabricks
+        - ChatDeepSeek
         - ChatGithub
         - ChatGoogle
         - ChatGroq
diff --git a/docs/get-started/models.qmd b/docs/get-started/models.qmd
index 9c011d1f..f0df7652 100644
--- a/docs/get-started/models.qmd
+++ b/docs/get-started/models.qmd
@@ -17,6 +17,7 @@ To see the pre-requisites for a given provider, visit the relevant usage page in
 | Name                     | Usage                                                    | Enterprise? |
 |--------------------------|----------------------------------------------------------|------------|
 | Anthropic (Claude)       | [`ChatAnthropic()`](../reference/ChatAnthropic.qmd)     |    |
+| DeepSeek                 | [`ChatDeepSeek()`](../reference/ChatDeepSeek.qmd)       |    |
 | GitHub model marketplace | [`ChatGithub()`](../reference/ChatGithub.qmd)           |    |
 | Google (Gemini)          | [`ChatGoogle()`](../reference/ChatGoogle.qmd)           |    |
 | Groq                     | [`ChatGroq()`](../reference/ChatGroq.qmd)               |    |
diff --git a/tests/test_provider_deepseek.py b/tests/test_provider_deepseek.py
new file mode 100644
index 00000000..8d617df1
--- /dev/null
+++ b/tests/test_provider_deepseek.py
@@ -0,0 +1,62 @@
+import os
+
+import pytest
+from chatlas import ChatDeepSeek
+
+from .conftest import (
+    assert_tools_async,
+    assert_tools_simple,
+    assert_turns_existing,
+    assert_turns_system,
+)
+
+api_key = os.getenv("DEEPSEEK_API_KEY")
+if api_key is None:
+    pytest.skip("DEEPSEEK_API_KEY is not set; skipping tests", allow_module_level=True)
+
+
+def test_deepseek_simple_request():
+    chat = ChatDeepSeek(
+        system_prompt="Be as terse as possible; no punctuation",
+    )
+    chat.chat("What is 1 + 1?")
+    turn = chat.get_last_turn()
+    assert turn is not None
+    assert turn.tokens is not None
+    assert len(turn.tokens) == 3
+    assert turn.tokens[0] >= 10  # More lenient assertion for DeepSeek
+    assert turn.finish_reason == "stop"
+
+
+@pytest.mark.asyncio
+async def test_deepseek_simple_streaming_request():
+    chat = ChatDeepSeek(
+        system_prompt="Be as terse as possible; no punctuation",
+    )
+    res = []
+    async for x in await chat.stream_async("What is 1 + 1?"):
+        res.append(x)
+    assert "2" in "".join(res)
+    turn = chat.get_last_turn()
+    assert turn is not None
+    assert turn.finish_reason == "stop"
+
+
+def test_deepseek_respects_turns_interface():
+    chat_fun = ChatDeepSeek
+    assert_turns_system(chat_fun)
+    assert_turns_existing(chat_fun)
+
+
+def test_deepseek_tool_variations():
+    chat_fun = ChatDeepSeek
+    assert_tools_simple(chat_fun)
+
+
+@pytest.mark.asyncio
+async def test_deepseek_tool_variations_async():
+    chat_fun = ChatDeepSeek
+    await assert_tools_async(chat_fun)
+
+
+# Doesn't seem to support data extraction or images