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Official Python SDK for the Market Data API providing real-time and historical U.S. stock and options market data. Access prices, quotes, options chains, and time series data for trading, quantitative research, analytics, and automated workflows.

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Market Data Python SDK v1.1

Access Financial Data with Ease

This is the official Python SDK for Market Data. It provides developers with a powerful, easy-to-use interface to obtain real-time and historical financial data. Ideal for building financial applications, trading bots, and investment strategies.

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Features

  • Real-time Stock Data: Prices, quotes, candles (OHLCV), earnings, and news
  • Options Trading Data: Complete options chains, expirations, strikes, quotes, and lookup
  • Mutual Funds: Historical candles and pricing data
  • Market Status: Real-time market open/closed status for multiple countries
  • Multiple Output Formats: DataFrames (pandas/polars), JSON, CSV, or Python objects
  • Built-in Retry Logic: Automatic retry with exponential backoff for reliable data fetching
  • Type-Safe: Full Pydantic validation and type hints
  • Zero Config: Works out of the box with sensible defaults

Requirements

  • Python >= 3.10

Installation

Basic Installation

Install from PyPI:

pip install marketdata-sdk-py

Or if you're using uv:

uv pip install marketdata-sdk-py

Installation with DataFrame Support

To use OutputFormat.DATAFRAME, you need to install at least one DataFrame library. See Optional Dependencies for details.

Install with pandas (recommended):

pip install "marketdata-sdk-py[pandas]"
# or using uv
uv pip install "marketdata-sdk-py[pandas]"

Install with polars:

pip install "marketdata-sdk-py[polars]"
# or using uv
uv pip install "marketdata-sdk-py[polars]"

Install with both:

pip install "marketdata-sdk-py[pandas,polars]"
# or using uv
uv pip install "marketdata-sdk-py[pandas,polars]"

Local Development Installation

For local development, install from the project directory:

pip install .
# or with optional dependencies
pip install ".[pandas]"

Configuration

The SDK requires a MarketData authentication token. You can provide it in two ways:

Option 1: Environment variable (recommended)

Create a .env file in the project root:

MARKETDATA_TOKEN=your_token_here

Option 2: Pass token directly

You can pass the token when creating a client instance:

from marketdata.client import MarketDataClient

client = MarketDataClient(token="your_token_here")

Usage

Create a client

from marketdata.client import MarketDataClient
from logging import Logger

# Token will be automatically obtained from MARKETDATA_TOKEN environment variable
client = MarketDataClient()

# Or provide the token explicitly
client = MarketDataClient(token="your_token_here")

# You can also provide a custom logger
custom_logger = get_logger()  # Your custom logger setup
client = MarketDataClient(token="your_token_here", logger=custom_logger)

Client Initialization Details:

  • The client automatically fetches rate limits by making a request to /user/ endpoint during initialization
  • The client includes a User-Agent header with the format marketdata-py-{version} (e.g., marketdata-py-0.0.1)
  • The library version is automatically detected from the installed package
  • All requests include an Authorization: Bearer {token} header
  • The client uses httpx.Client for HTTP requests with automatic connection pooling

Accessing Rate Limits

The client automatically fetches and tracks rate limits from the API. Rate limits are initialized when the client is created by making a request to /user/ endpoint, and are updated after each API request based on response headers.

You can access current rate limits:

client = MarketDataClient()

# Access current rate limits
rate_limits = client.rate_limits

# Access individual fields
print(f"Limit: {rate_limits.requests_limit}")
print(f"Remaining: {rate_limits.requests_remaining}")
print(f"Consumed: {rate_limits.requests_consumed}")
print(f"Reset at: {rate_limits.requests_reset}")

# Or use the formatted string representation
print(rate_limits)  # Shows: "Rate used X/Y, remaining: Z credits, next reset: ISO timestamp"

Note: Rate limits are tracked via the following response headers:

  • x-api-ratelimit-limit: Total number of requests allowed
  • x-api-ratelimit-remaining: Number of requests remaining
  • x-api-ratelimit-consumed: Number of requests consumed
  • x-api-ratelimit-reset: Unix timestamp when the rate limit resets

The requests_reset field is automatically converted to a datetime.datetime object for easier use.

Resources

The SDK provides access to different market data resources:

  • Stocks: Access stock prices, quotes, candles (OHLCV), earnings, and news

    • Methods: prices(), quotes(), candles(), earnings(), news()
    • See Stocks Documentation for detailed usage
  • Options: Access options chains, expiration data, strikes, quotes, and lookup

    • Methods: chain(), expirations(), strikes(), quotes(), lookup()
    • See Options Documentation for detailed usage
  • Funds: Access funds candles (OHLC) for mutual funds

  • Markets: Access market status information (open/closed) for dates and countries

Note: For stocks, options, and funds resources, the symbol, symbols, or lookup parameter (depending on the method) can be passed as the first positional argument or as a keyword argument. All other parameters must be keyword-only. For markets resource, all parameters must be keyword-only.

Quick Example

from marketdata.client import MarketDataClient

client = MarketDataClient()

# Get stock prices (symbols can be passed positionally or as keyword)
df = client.stocks.prices("AAPL")
# or
df = client.stocks.prices(symbols="AAPL")
print(df)

# Get stock candles (symbol can be passed positionally or as keyword)
df = client.stocks.candles("AAPL")
# or
df = client.stocks.candles(symbol="AAPL")
print(df)

# Get options chain (symbol can be passed positionally or as keyword)
chain = client.options.chain("AAPL")
# or
chain = client.options.chain(symbol="AAPL")
print(chain)

# Get options strikes (symbol can be passed positionally or as keyword)
strikes = client.options.strikes("AAPL")
# or
strikes = client.options.strikes(symbol="AAPL")
print(strikes)

# Get options quotes (symbols can be passed positionally or as keyword)
# Note: quotes() takes option symbols (e.g., "AAPL240120C00150000"), not stock symbols
quotes = client.options.quotes("AAPL240120C00150000")
# or
quotes = client.options.quotes(symbols="AAPL240120C00150000")
print(quotes)

# Get options lookup (lookup can be passed positionally or as keyword)
# Format: "SYMBOL DD-MM-YYYY STRIKE SIDE" (e.g., "AAPL 20-12-2024 150.0 call")
lookup = client.options.lookup("AAPL 20-12-2024 150.0 call")
# or
lookup = client.options.lookup(lookup="AAPL 20-12-2024 150.0 call")
print(lookup)

# Get funds candles (symbol can be passed positionally or as keyword)
df = client.funds.candles("VFINX")
# or
df = client.funds.candles(symbol="VFINX")
print(df)

# Get market status (all parameters must be keyword-only)
df = client.markets.status(countback=7)
print(df)

Output Formats

The SDK supports multiple output formats for API responses. See the Universal Parameters section for details on how to specify output formats.

  • OutputFormat.DATAFRAME: Returns a pandas or polars DataFrame (default). Requires installing pandas or polars as an optional dependency. See Optional Dependencies for installation instructions.
  • OutputFormat.INTERNAL: Returns internal Python objects (see resource-specific documentation for details)
  • OutputFormat.JSON: Returns raw JSON data (dictionary)
  • OutputFormat.CSV: Writes CSV data to file and returns filename string

For detailed information about return types and object structures for each resource, see the specific resource documentation:

You can specify the output format when calling resource methods:

from marketdata.client import MarketDataClient
from marketdata.input_types.base import OutputFormat

client = MarketDataClient()

# Get DataFrame (default) - symbols can be passed positionally or as keyword
df = client.stocks.prices("AAPL")
# or
df = client.stocks.prices(symbols="AAPL")

# Get internal objects
prices = client.stocks.prices("AAPL", output_format=OutputFormat.INTERNAL)
# or
prices = client.stocks.prices(symbols="AAPL", output_format=OutputFormat.INTERNAL)

# Get JSON
json_data = client.stocks.prices("AAPL", output_format=OutputFormat.JSON)
# or
json_data = client.stocks.prices(symbols="AAPL", output_format=OutputFormat.JSON)

# Get CSV
# All methods write to file and return filename string
csv_file = client.stocks.prices("AAPL", output_format=OutputFormat.CSV, filename="prices.csv")
# Get candles as internal objects
candles = client.stocks.candles("AAPL", output_format=OutputFormat.INTERNAL)
# If filename is not provided, a timestamped file is created in output/ directory
csv_file = client.options.chain("AAPL", output_format=OutputFormat.CSV)

CSV Output Behavior

When using OutputFormat.CSV, all resources write CSV data to a file and return the filename as a string. If filename is not provided, a timestamped file is automatically created in the output/ directory (the directory is created if it doesn't exist).

Note: When specifying a custom filename, the directory must exist and the file must not already exist. See resource-specific documentation for details on CSV output format.

Universal Parameters

All resource methods support universal parameters that can be used to customize the API request and response:

output_format (OutputFormat, optional)

The format of the returned data. Defaults to OutputFormat.DATAFRAME.

date_format (DateFormat, optional)

The date format to use in the response. Defaults to DateFormat.UNIX. Available options:

  • DateFormat.TIMESTAMP: ISO timestamp format
  • DateFormat.UNIX: Unix timestamp (seconds since epoch)
  • DateFormat.SPREADSHEET: Spreadsheet-compatible format

columns (list[str], optional)

Specify which columns to include in the response. If not provided, all available columns are returned.

add_headers (bool, optional)

Whether to include headers in the response. Uses API alias headers.

use_human_readable (bool, optional)

Whether to use human-readable format for values. Uses API alias human.

mode (Mode, optional)

The data feed mode to use. Available options:

  • Mode.LIVE: Live market data
  • Mode.CACHED: Cached data
  • Mode.DELAYED: Delayed data

filename (str | Path, optional)

File path for CSV output (only used with output_format=OutputFormat.CSV).

  • Must end with .csv
  • Directory must exist (if filename is provided)
  • File must not already exist
  • If not provided, a timestamped file is created in output/ directory (the directory is automatically created if it doesn't exist)

Example: Using Universal Parameters

from marketdata.client import MarketDataClient
from marketdata.input_types.base import OutputFormat, DateFormat, Mode
from pathlib import Path

client = MarketDataClient()

# Use custom date format and mode
df = client.stocks.prices(
    "AAPL",
    date_format=DateFormat.TIMESTAMP,
    mode=Mode.LIVE
)

# Specify columns to include
df = client.stocks.prices(
    "AAPL",
    columns=["symbol", "mid", "change_percent"]
)

# Save CSV with custom filename
csv_file = client.stocks.prices(
    "AAPL",
    output_format=OutputFormat.CSV,
    filename=Path("data/aapl_prices.csv")
)

Error Handling

The SDK uses a combination of exceptions and return values for error handling:

RateLimitError

Raised when API rate limits are exceeded (before retry logic):

from marketdata.client import MarketDataClient
from marketdata.exceptions import RateLimitError

try:
    client = MarketDataClient()
    df = client.stocks.prices("AAPL")
    # or
    df = client.stocks.prices(symbols="AAPL")
except RateLimitError as e:
    print(f"Rate limit exceeded: {e}")

RequestError

Raised for HTTP errors and retryable status codes. This exception is used internally by the retry mechanism. When a retryable status code (status code > 500 by default) is encountered, a RequestError is raised, which triggers the retry logic. After retries are exhausted or if the service is offline, the exception is caught by @handle_exceptions and converted to MarketDataClientErrorResult.

Note: This exception is typically caught internally by the @handle_exceptions decorator and converted to MarketDataClientErrorResult. You generally won't need to catch it directly unless you're working with the low-level make_request method.

ValueError

Raised for various validation errors:

  • Invalid date formats when parsing timestamps
  • Invalid output format values
  • Invalid filename format (must end with .csv, directory must exist, file must not exist)
  • Invalid input parameters
from marketdata.client import MarketDataClient
from marketdata.input_types.base import OutputFormat
from pathlib import Path

try:
    client = MarketDataClient()
    # Invalid filename (doesn't end with .csv)
    csv_file = client.stocks.prices(
        "AAPL",
        output_format=OutputFormat.CSV,
        filename=Path("data/invalid.txt")
    )
except ValueError as e:
    print(f"Validation error: {e}")

MinMaxDateValidationError

Raised when date range validation fails (e.g., from_date is greater than to_date). This exception is typically caught internally by the @handle_exceptions decorator and converted to MarketDataClientErrorResult. You generally won't need to catch it directly unless you're working with low-level validation.

from marketdata.client import MarketDataClient
from marketdata.exceptions import MinMaxDateValidationError
from marketdata.sdk_error import MarketDataClientErrorResult
import datetime

try:
    client = MarketDataClient()
    # Invalid date range (from_date > to_date)
    result = client.stocks.candles(
        "AAPL",
        from_date=datetime.date(2024, 12, 31),
        to_date=datetime.date(2024, 1, 1)
    )
    if isinstance(result, MarketDataClientErrorResult):
        if isinstance(result.error, MinMaxDateValidationError):
            print(f"Date range validation error: {result.error}")
except MinMaxDateValidationError as e:
    print(f"Validation error: {e}")

KeywordOnlyArgumentError

Raised when arguments are passed incorrectly. Only the symbol or symbols parameter can be passed as a positional argument. All other parameters must be keyword-only:

from marketdata.client import MarketDataClient
from marketdata.exceptions import KeywordOnlyArgumentError
from marketdata.input_types.base import OutputFormat

try:
    client = MarketDataClient()
    # ❌ This will raise KeywordOnlyArgumentError
    df = client.stocks.prices("AAPL", OutputFormat.DATAFRAME)
    
    # ✅ Correct usage
    df = client.stocks.prices("AAPL", output_format=OutputFormat.DATAFRAME)
    # or
    df = client.stocks.prices(symbols="AAPL", output_format=OutputFormat.DATAFRAME)
except KeywordOnlyArgumentError as e:
    print(f"Invalid argument usage: {e}")

MarketDataClientErrorResult

This is a special result type returned by resource methods when errors occur. It wraps the original exception and allows you to check for errors without exception handling. All resource methods return either the expected result or MarketDataClientErrorResult - they never return None.

from marketdata.client import MarketDataClient
from marketdata.sdk_error import MarketDataClientErrorResult

client = MarketDataClient()
result = client.stocks.prices("AAPL")

# Check if the result is an error
if isinstance(result, MarketDataClientErrorResult):
    print(f"Error occurred: {result.error}")
    print(f"Error type: {type(result.error).__name__}")
else:
    print(result)

The MarketDataClientErrorResult object contains the original exception in its error attribute, which can be:

  • RateLimitError: When rate limits are exceeded
  • MinMaxDateValidationError: When date range validation fails (e.g., from_date > to_date)
  • ValueError: When input validation fails (invalid formats, filenames, etc.)
  • RequestError: When HTTP requests fail
  • BadStatusCodeError: When HTTP requests return non-retryable error status codes
  • Any other exception that occurs during request processing

Retry Mechanism

The SDK includes automatic retry logic for handling transient errors. The retry mechanism is triggered when a RequestError exception occurs in methods decorated with @api_error_handler.

Retry Configuration

  • Default retry attempts: 3
  • Backoff strategy: Exponential with multiplier 0.5, minimum wait 0.5 seconds, maximum wait 5 seconds
  • Retryable status codes: The SDK retries on any HTTP status code greater than 500 (server errors). This includes common server error codes like 502 (Bad Gateway), 503 (Service Unavailable), 504 (Gateway Timeout), and others.
  • Default timeout: 60 seconds per request

How It Works

The retry mechanism only retries on RequestError exceptions and only if the API service status is ONLINE or UNKNOWN. When a retryable status code is encountered, a RequestError exception is raised internally, which triggers the retry logic. The retry adapter uses the tenacity library and will retry up to the specified number of attempts with exponential backoff between retries.

Important: Resource methods always return a value. They may return:

  • The expected result (DataFrame, list of objects, dict, or str for CSV)
  • MarketDataClientErrorResult if an error occurs (rate limits, validation errors, request failures, etc.)

Exceptions are caught internally by the @handle_exceptions decorator and converted to MarketDataClientErrorResult. However, some exceptions may still be raised before reaching the decorator (e.g., RateLimitError when rate limits cannot be checked).

Always check for MarketDataClientErrorResult return values and handle exceptions when calling resource methods:

from marketdata.client import MarketDataClient
from marketdata.exceptions import RateLimitError, RequestError
from marketdata.sdk_error import MarketDataClientErrorResult

client = MarketDataClient()
try:
    result = client.stocks.prices("AAPL")
    # Check if the result is an error
    if isinstance(result, MarketDataClientErrorResult):
        print(f"Request failed: {result.error}")
        print(f"Error type: {type(result.error).__name__}")
    else:
        print(result)
except (RateLimitError, RequestError) as e:
    # These exceptions may be raised before reaching the decorator
    print(f"Request failed: {e}")

API Status Checking

The SDK includes automatic API status checking for certain resource methods. When a RequestError occurs, the SDK verifies that the API service is online before retrying the request.

How It Works

  • Automatic checking: Methods with API status checking (@api_error_handler decorator) verify service availability when a RequestError occurs
  • Cached status: API status information is cached and refreshed automatically every 4 minutes and 30 seconds
  • Service-specific: Each method checks the status of its specific service endpoint
  • Retry logic: The SDK only retries requests if the service status is ONLINE or UNKNOWN. If the service is OFFLINE, the error is raised immediately

Methods with API Status Checking

All resource methods include API status checking and automatic retry logic. See the specific resource documentation for details on each method's behavior.

Error Handling

If a service is offline when checked, the method raises the original RequestError exception instead of retrying:

from marketdata.client import MarketDataClient
from marketdata.exceptions import RequestError

client = MarketDataClient()
try:
    result = client.stocks.candles("AAPL")
except RequestError as e:
    print(f"Service unavailable or request failed: {e}")

Status Refresh Behavior

The SDK automatically refreshes the API status cache when:

  • The cached status is older than 4 minutes and 30 seconds
  • A RequestError occurs in a method with status checking

The status refresh request does not count against rate limits (check_rate_limits=False) and does not update rate limit tracking (populate_rate_limits=False), ensuring that status checking does not interfere with your API usage while providing up-to-date service availability information.

Advanced Configuration

You can customize the base URL, API version, logging level, and universal parameters through environment variables:

# Required
MARKETDATA_TOKEN=your_token_here

# API Configuration
MARKETDATA_BASE_URL=https://api.marketdata.app
MARKETDATA_API_VERSION=v1
MARKETDATA_LOGGING_LEVEL=INFO

# Universal Parameters (optional - can also be passed as method arguments)
MARKETDATA_OUTPUT_FORMAT=dataframe
MARKETDATA_DATE_FORMAT=unix
MARKETDATA_COLUMNS=symbol,mid,change_percent
MARKETDATA_ADD_HEADERS=true
MARKETDATA_USE_HUMAN_READABLE=false
MARKETDATA_MODE=live

Defaults:

  • MARKETDATA_BASE_URL: https://api.marketdata.app
  • MARKETDATA_API_VERSION: v1
  • MARKETDATA_LOGGING_LEVEL: INFO
  • Universal parameters: None (uses method defaults)

Note: Universal parameters set via environment variables will be used as defaults for all API calls, but can be overridden by passing them as method arguments. See the Universal Parameters section for available values.

Project Structure

.
├── docs/
│   ├── stocks.md         # Stocks resource documentation
│   ├── options.md        # Options resource documentation
│   ├── funds.md          # Funds resource documentation
│   └── markets.md        # Markets resource documentation
├── src/
│   ├── tests/            # Test suite
│   │   ├── conftest.py   # Pytest configuration and fixtures
│   │   ├── test_client.py
│   │   ├── test_stocks_prices.py
│   │   ├── test_stocks_candles.py
│   │   ├── test_options_chain.py
│   │   ├── test_options_expirations.py
│   │   ├── test_options_quotes.py
│   │   ├── test_params.py
│   │   └── data/         # Test data fixtures
│   └── marketdata/
│       ├── __init__.py
│       ├── client.py          # Main MarketDataClient class
│       ├── exceptions.py      # Custom exceptions (RateLimitError, RequestError, KeywordOnlyArgumentError)
│       ├── logger.py          # Logging configuration
│       ├── params.py          # Parameter decorators and validation (@universal_params)
│       ├── retry.py           # Retry mechanism using tenacity
│       ├── settings.py        # Configuration and environment variables
│       ├── types.py           # Data types (UserRateLimits)
│       ├── utils.py           # Utility functions (format_timestamp, initialize_dataframe, etc.)
│       ├── docs.py            # Documentation generation utilities
│       ├── internal_settings.py  # Internal settings (MAX_CONCURRENT_REQUESTS)
│       ├── input_types/       # Input validation types
│       │   ├── __init__.py
│       │   ├── base.py        # Base input type classes (OutputFormat, DateFormat, Mode, UserUniversalAPIParams)
│       │   ├── stocks.py      # Stocks input types (StocksPricesInput, StocksQuotesInput, StocksCandlesInput)
│       │   ├── funds.py       # Funds input types (FundsCandlesInput)
│       │   ├── markets.py     # Markets input types (MarketStatusInput)
│       │   └── options.py     # Options input types (OptionsChainInput, OptionsExpirationsInput, OptionsStrikesInput, OptionsQuotesInput, OptionsLookupInput)
│       ├── output_types/      # Output data types
│       │   ├── __init__.py
│       │   ├── stocks_prices.py  # Stock prices output types (StockPrice, StockPricesHumanReadable)
│       │   ├── stocks_quotes.py  # Stock quotes output types (StockQuote, StockQuotesHumanReadable)
│       │   ├── stocks_candles.py  # Stock candles output types (StockCandle, StockCandlesHumanReadable)
│       │   ├── stocks_earnings.py  # Stock earnings output types (StockEarnings, StockEarningsHumanReadable)
│       │   ├── stocks_news.py  # Stock news output types (StockNews, StockNewsHumanReadable)
│       │   ├── funds_candles.py   # Funds candles output types (FundsCandle, FundsCandlesHumanReadable)
│       │   ├── markets_status.py  # Markets status output types (MarketStatus, MarketStatusHumanReadable)
│       │   ├── options_chain.py   # Options chain output types (OptionsChain)
│       │   ├── options_expirations.py  # Options expirations output types (OptionsExpirations)
│       │   ├── options_quotes.py  # Options quotes output types (OptionsQuotes)
│       │   ├── options_strikes.py  # Options strikes output types (OptionsStrikes)
│       │   └── options_lookup.py  # Options lookup output types (OptionsLookup)
│       └── resources/
│           ├── __init__.py
│           ├── base.py        # BaseResource class with common functionality
│           ├── stocks/        # Stocks API resource
│           │   ├── __init__.py  # StocksResource class definition
│           │   ├── prices.py  # Stock prices endpoint
│           │   ├── quotes.py  # Stock quotes endpoint
│           │   ├── candles.py # Stock candles endpoint
│           │   ├── earnings.py # Stock earnings endpoint
│           │   └── news.py    # Stock news endpoint
│           ├── funds/         # Funds API resource
│           │   ├── __init__.py  # FundsResource class definition
│           │   └── candles.py # Funds candles endpoint
│           ├── markets/       # Markets API resource
│           │   ├── __init__.py  # MarketsResource class definition
│           │   └── status.py  # Markets status endpoint
│           └── options/       # Options API resource
│               ├── __init__.py  # OptionsResource class definition
│               ├── chain.py   # Options chain endpoint
│               ├── expirations.py  # Options expirations endpoint
│               ├── strikes.py  # Options strikes endpoint
│               ├── quotes.py  # Options quotes endpoint
│               └── lookup.py  # Options lookup endpoint
└── pyproject.toml        # Project configuration and dependencies

Dependencies

Required

  • httpx>=0.28.1: HTTP client library for making API requests
  • pydantic>=2.12.5: Data validation and settings management
  • pydantic-settings>=2.12.0: Configuration management from environment variables
  • tenacity>=9.1.2: Retry logic library for handling transient errors

Optional Dependencies

The SDK supports multiple DataFrame libraries for OutputFormat.DATAFRAME. You must install at least one of the following:

  • pandas (recommended): pandas>=2.3.3
  • polars: polars-lts-cpu>=1.33.1

Installation

Install with pandas (recommended):

pip install "marketdata-sdk-py[pandas]"
# or using uv
uv pip install "marketdata-sdk-py[pandas]"

Install with polars:

pip install "marketdata-sdk-py[polars]"
# or using uv
uv pip install "marketdata-sdk-py[polars]"

Install with both:

pip install "marketdata-sdk-py[pandas,polars]"
# or using uv
uv pip install "marketdata-sdk-py[pandas,polars]"

DataFrame Handler Priority

When using OutputFormat.DATAFRAME, the SDK automatically selects an available DataFrame library in the following order:

  1. pandas (if installed)
  2. polars (if pandas is not installed)

If neither pandas nor polars is installed, a ValueError will be raised when attempting to use OutputFormat.DATAFRAME:

ValueError: No dataframe output handler found

Note: You can use other output formats (OutputFormat.INTERNAL, OutputFormat.JSON, OutputFormat.CSV) without installing pandas or polars.

Development Dependencies

  • black>=25.11.0: Code formatter
  • isort>=7.0.0: Import sorter
  • pandas>=2.3.3: DataFrame library (for testing)
  • polars-lts-cpu>=1.33.1: DataFrame library (for testing)
  • pytest>=9.0.1: Testing framework
  • respx>=0.22.0: HTTPX mocking library for tests

Implementation Details

Date Format Handling

The SDK automatically handles multiple date formats:

  • ISO timestamp strings: Parsed using datetime.fromisoformat()
  • Unix timestamps: Parsed using datetime.fromtimestamp() (seconds since epoch)
  • Spreadsheet dates: Values between 0 and 60000 are treated as Excel-style dates (days since 1899-12-30)

All timestamps in response objects are automatically converted to datetime.datetime objects when using OutputFormat.INTERNAL. When using OutputFormat.DATAFRAME, timestamp conversion behavior varies by resource. See the specific resource documentation for details.

DataFrame Processing

When using OutputFormat.DATAFRAME, the SDK performs automatic data cleaning:

  • The s (status) column is removed from all DataFrames
  • DataFrames are automatically indexed by their primary identifier (see resource-specific documentation for details)
  • Timestamp columns are converted to datetime.datetime objects in most cases (see resource-specific documentation for exceptions)

For detailed information about DataFrame structure and indexing for each method, see the specific resource documentation.

Parameter Validation

The SDK uses Pydantic for input validation:

  • All input parameters are validated using Pydantic models
  • Boolean parameters are converted to lowercase strings for the API ("true"/"false")
  • List parameters are joined with commas
  • Enum parameters use their .value attribute
  • Date parameters are formatted appropriately for the API

Concurrent Requests

The SDK uses concurrent requests for efficient data fetching in specific scenarios:

  • stocks.candles(): For intraday resolutions (minutely/hourly), large date ranges are automatically split into year-long chunks and fetched concurrently (up to 50 concurrent requests by default)
  • options.quotes(): Multiple option symbols are fetched concurrently (up to 50 concurrent requests by default)

When concurrent requests are used, responses are automatically merged into a single result. If no valid responses are received, a MarketDataClientErrorResult is returned.

See the specific resource documentation for details on concurrent request behavior.

Rate Limit Tracking

Rate limits are tracked via response headers and updated after each request:

  • Rate limit information is extracted from response headers after every API call
  • The UserRateLimits object is updated automatically
  • Rate limit checking happens before each request (unless check_rate_limits=False)
  • If rate limits are exhausted, a RateLimitError is raised before making the request

Development

Linting

./lint.sh

Build

./build.sh

License

See the LICENSE file for more details.

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Official Python SDK for the Market Data API providing real-time and historical U.S. stock and options market data. Access prices, quotes, options chains, and time series data for trading, quantitative research, analytics, and automated workflows.

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