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You can subscribe to the RSS changelog at /changelog.rss if you’d like to stay ahead of breaking changes. You can reference the pending API spec under the “version” dropdown menu at the top left. When the actual API is upgraded to this new version, you will see the version marked as “Stable” in the drop-down menu and become the new default on the landing page. This changelog is a work in progress. As always, we welcome any feedback in our Discord #dev channel!

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Recent Updates

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Dec 2, 2025
Breaking Change: GET /events excludes multivariate eventsRelease date: December 4, 2025
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Dec 1, 2025
Release date: December 4, 2025
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Dec 1, 2025
DELETE /portfolio/orders/batched is now generally available. Advanced API access is no longer required. (The Nov 14th update only applied to POST.)Release date: December 4, 2025
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Nov 29, 2025
GET /live_data/{type}/milestone/{milestone_id} and GET /live_data/batch now returns milestone_id in the response.Release date: December 4, 2025
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Nov 23, 2025
Updates to filtering in GET /markets
  • Inactive markets during tradable hours will returned in the open selector.
  • Inactive markets during tradable hours no longer appear in the closed selector.
  • Restricting to a single status filter allowed per request (previously announced).
Release date: November 27, 2025
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Nov 21, 2025
Subpenny fields yes_bid_dollars and no_bid_dollars available on the Get Quote API. Affected endpoints:
  • GET /communications/quotes
  • GET /communications/quotes/{quote_id}
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Nov 27, 2025
Adds new endpoint GET /markets/candlesticksRetrieve candlestick data for multiple markets in a single API call. Supports up to 10,000 candlesticks total across all requested markets.Expected release: November 27, 2025
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Nov 21, 2025
Breaking changes to order expiration and immediate-or-cancel (IoC) handling:
  1. Past expiration timestamps now rejected: Orders with expiration_ts in the past will be rejected with error “Expiration timestamp must be in the future” instead of being automatically converted to IoC orders.
  2. IoC + expiration_ts combination rejected: Orders cannot specify both time_in_force: "immediate_or_cancel" and expiration_ts. This will be rejected at the API level with error “Cannot specify both immediate_or_cancel and expiration_ts”.
  3. IoC orders no longer support expiration: The IoC order type is now independent and does not accept an expiration timestamp.
Migration guide: If you were previously using past expiration_ts values to indicate IoC behavior, you must now explicitly set time_in_force: "immediate_or_cancel" instead.Expected release: TBD
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Nov 20, 2025
‘Pending’ is being removed from the status enum on ordersExpected release: November 27, 2025
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Nov 14, 2025
POST /portfolio/orders/batched will now be generally available. Advanced API access is no longer a prerequisite.Release date: November 20, 2025
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Nov 14, 2025
Added created_time to GET /markets && GET /market responses.Release date: November 20, 2025
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Nov 11, 2025
Breaking changes planned to GET /markets endpoint for performance reasons: Timestamp filters will be mutually exclusive from other timestamp filters and certain status filters.
Compatible Timestamp FiltersAdditional Status Filters
min_created_ts, max_created_tsunopened, open, empty
min_close_ts, max_close_tsclosed, empty
min_settled_ts, max_settled_tssettled, empty
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Nov 11, 2025
Added new timestamp filters for the GET /markets endpoint:
  • min_created_ts
  • max_created_ts
  • min_settled_ts
  • max_settled_ts
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Nov 7, 2025
  • GET /portfolio/positions will no longer return resting_orders_count in both the event_positions and market_positions field.
  • The resting_order_count filter on GET /portfolio/positions will no longer be supported. Requests specifying this filter will return a 400 error.
Expected release: November 13, 2025
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Nov 13, 2025
GET /portfolio/settlements now returns the sum of trade fees paid by the user on a settled market position.
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Nov 6, 2025
Fixed two issues with the GET /events endpoint’s limit parameter:
  • Default increased: The default limit is now 200 (previously 100) to return more results per page
  • Parameter: Requests with with_nested_markets=true now properly respect limit=200 instead of being capped at 100
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Nov 6, 2025
The GET /portfolio/positions endpoint now includes total_cost_shares, which tracks the total number of shares traded on an event (including both YES and NO contracts).
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Nov 6, 2025
Added comprehensive support for multivariate events (combos) with new API endpoints and enhanced filtering:New Endpoint and deprecation of multivariate events in GetEvents endpoint
  • GET /events/multivariate - Retrieve multivariate events with filtering by series and collection ticker.
  • GET /events will EXCLUDE multivariate events upon the next release (November 13th). Please use the new endpoint!
Enhanced Market Filtering:
  • GET /markets now supports mve_filter parameter:
    • "only" - Returns only multivariate events
    • "exclude" - Excludes multivariate events
    • No parameter - Returns all events (default behavior)
Expected release: November 6th, 2025
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Oct 24, 2025
Fixed batch order creation to return proper error details when post-only orders cross the market. The response now includes:
  • Error code: "invalid order"
  • Error details: "post only cross"
This makes the batch endpoint consistent with single order creation and provides clear feedback on why post-only orders were rejected.
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Oct 20, 2025
The GET /portfolio/orders endpoint’s event_ticker parameter now supports filtering by multiple events using comma-separated values.Example usage:
GET /portfolio/orders?event_ticker=EVENT1,EVENT2,EVENT3
Backward Compatible:
  • Single event ticker queries continue to work as before
  • Multiple event tickers return orders from all specified events
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Oct 19, 2025
Fixed missing fields in Quote responses: rfq_target_cost_centi_cents, rfq_creator_order_id, and creator_order_id are now properly included in all Quote-related endpoints.
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Oct 16, 2025
The GET /events endpoint now supports an optional flag, with_milestones, that includes all milestones related to the returned events.Expected release: October 16, 2025
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Oct 14, 2025
The order returned by create order is now the same model as the model returned by get order.
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Oct 13, 2025
The GET /v2/incentive_programs and GET /incentive_programs endpoints now return a series_ticker field for each incentive program.Expected release: October 13, 2025
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Oct 10, 2025
The price_level_structure field has been moved from the event level to the market level. Each market now has its own price_level_structure field.Affected endpoints:
  • GET /trade-api/v2/events
  • GET /trade-api/v2/events/:event_ticker
  • GET /trade-api/v2/markets
  • GET /trade-api/v2/markets/:ticker
Note: The price_level_structure field on event objects is now deprecated and will be removed. Please use the field on individual market objects instead.Expected release date: Oct 15th, 2025
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Oct 13, 2025
Fixed the GET /series endpoint’s tags parameter to properly support tags containing spaces. Previously, the parameter would split on both commas AND spaces, breaking searches for tags like “Rotten Tomatoes”.Breaking Change:
  • The tags query parameter now only splits on commas (,), not spaces
  • Tags with spaces (e.g., “Rotten Tomatoes”) now work correctly
  • Multiple tags must be comma-separated: ?tags=Rotten Tomatoes,Television
Before (broken):
GET /series?tags=Rotten Tomatoes
// Was incorrectly parsed as: ["Rotten", "Tomatoes"]
// Result: No matches found
After (fixed):
GET /series?tags=Rotten Tomatoes
// Correctly parsed as: ["Rotten Tomatoes"]
// Result: Returns series with the "Rotten Tomatoes" tag

GET /series?tags=Rotten Tomatoes,Television
// Correctly parsed as: ["Rotten Tomatoes", "Television"]
// Result: Returns series with either tag
This change may affect integrations that relied on space-separated tags. Please update to use comma-separated tags only.
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Oct 8, 2025
Fixed routing inconsistency where certain collection endpoints required trailing slashes, causing unnecessary 301 redirects for requests without them.Endpoints now returning 200 for requests without trailing slash (previously returned 301):
  • GET /milestones
  • GET /structured_targets
  • GET /multivariate_event_collections
  • GET /series
  • GET /api_keys
  • POST /api_keys
Note: Requests with trailing slashes (e.g., /milestones/) will now receive a 301 redirect to the version without the trailing slash, which is the opposite of the previous behavior.
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Oct 9, 2025
Subpenny fields have been added to orders (taker_fees_dollars, maker_fees_dollars), as well as to public trades (yes_price_dollars, no_price_dollars).Endpoints affected:
  • GET /trade-api/v2/portfolio/orders
  • GET /trade-api/v2/markets/trades
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Oct 9, 2025
Fields have been added to all RFQ and quote messages to support subpenny pricing via the dollar normalized price fields. For more info reference:
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Oct 7, 2025
Enhanced the existing GET /portfolio/balance endpoint to include a portfolio_value field that provides the total portfolio value (available balance plus current market value of all positions), both in cents.
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Oct 1, 2025
The GET /series/fee_changes endpoint now returns user-facing fee type names (quadratic, quadratic_with_maker_fees, flat) instead of internal fee structure names. This change also applies to CustomerIO notifications for scheduled series fee updates.Expected release: October 1, 2025
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Sep 25, 2025
Repeated subscriptions on the same websocket call will no longer error. If passing the same market tickers as before, no action will be taken. If passing new market tickers, they will be added to your existing subscription.Additionally, the user may supply WS Command list_subscriptions to view their existing subscriptions.Expected release: October 1, 2025
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Sep 25, 2025
For optimization purposes, partial fills generated by self-crossing FoK orders are not rolled back. If a FoK order self-crosses, order execution proceeds based on self_trade_prevention_type:
  • taker_at_cross: the taker is canceled, execution stops. Any partial fills are executed.
  • maker: the maker is canceled, execution continues. After execution, remaining taker quantity is canceled. Any fills are executed.
This fixes a bug where partially filled FoK orders with Maker STP entered into the book after self-crossing. Expected enforced date: Oct 1, 2025.
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Sep 22, 2025
User seeking a simple way to determine the direction of their fill should reference purchased_side. Both BUY YES or SELL NO result in purchased_side = YES. The addition of this field is the first step in standardizing the fills websocket and REST endpoints, which have different conventions for the interpretation ‘side’ and ‘user_action’.Expected Enforce Date: deprecation date for existing fields not yet scheduled.
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Sep 21, 2025
Added new public API endpoint for getting all of a series’ scheduled fees:
  • GET /series/fee_changes - Get a series’ fee changes. If query string parameter show_historical is set to true, ALL fee changes previous and upcoming will be shown. If set to false, only upcoming fee changes will be shown
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Sep 25, 2025
Specifying order_type is no longer required and only limit type orders will be supported. Price must be supplied based on the underlying market structure. Example usage:
{"yes_price": 99, "side: "yes"} // buy yes or sell no at market price
{"no_price": 99, "side: "no"} // buy no or sell yes at market price
Expected enforce date: Sep 25, 2025
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Sep 18, 2025
WebSocket connections per user are limited by usage tier. The default limit begins at 200 and increases based on API usage tier.
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Sep 18, 2025
A new WS channel is being introduced for streaming information related to pre-trade communications (RFQs and quotes).
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Sep 15, 2025
Additional metadata is being added to RFQs on multivarate events (MVEs) that break down their component parts explicitly. Market payloads are also being expanded with these new optional fields that are filled only for MVE markets.
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Sep 15, 2025
Added new public API endpoint for event candlesticks:
  • GET /candlesticks - Get candlesticks for all markets associated with an event. If the # of candlesticks exceeds 5000, paginate the results and return an adjustedEndTs which should be used as the start_ts for your next request.
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Sept 11, 2025
The TypeScript SDK is now available through NPM! Install with npm install kalshi-typescript.Documentation and examples available at docs.kalshi.com
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Sep 11, 2025
Added new public API endpoint for forecast percentiles history:
  • GET /forecast_percentiles_history - Get percentile history of a event forecast
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Sep 10, 2025
Added new public API endpoint for incentive programs (not yet live):
  • GET /incentive_programs - List incentive programs with filtering options (by market ticker, active status, payout status)
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Sep 9, 2025
Subpenny pricing fields have been added to websocket messages. Any message bearing price in cents will now also bear an equivalent fixed-point dollars field.For more info, see Subpenny Pricing.
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Sep 9, 2025
Both the individual and batch GET events endpoints now also return available_on_brokers which indicates that they are available on intermediate platforms/ brokers.
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Sep 6, 2025
The python SDK is being generated from our OpenAPI spec and is available through pip with pip install kalshi-python. Docs for the new SDK are available on docs.kalshi.com/python-sdk.
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Aug 31, 2025
Subpenny pricing fields have been added to APIs involving price, fees, and money in general. E.g. next to a field called "price": 12 (representing 12 cents), you will also see "price_dollars": "0.1200", which is a string bearing a fixed-point representation of money accuate to at 4 decimal points.For now, this change is read-only, meaning that the minimum allowable tick size for orders is still 1c. Eventually, we will introduce sub-penny pricing on orders. For now, please prepare for an eventual migration to the higher granularity price representation.For more info, see Subpenny Pricing.
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Sep 2, 2025
The market payload has been updated to include two new fields that describe markets which are part of Multivariate Events.
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Sep 2, 2025
The market payload has been updated to include two new fields that describe markets which are part of Multivariate Events.
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Aug 21, 2025
The MVE payload has been expanded to support more flexible structures. Several fields that are now redundant are deprecated, but not yet removed.
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Aug 21, 2025
The Settlements API now includes the settlement value for a yes contract.
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Aug 21, 2025
The get_milestones endpoint now uses case-insensitive matching for the category parameter, resolving inconsistent filtering behavior between “Sports” and “sports”.
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Aug 14, 2025
Filtering events by close ts and series by tags supported in the API.
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Aug 13, 2025
The batch order endpoints are now available to all API users in the demo environment:Affected Endpoints:
  • POST /portfolio/orders/batched (BatchCreateOrders)
  • DELETE /portfolio/orders/batched (BatchCancelOrders)
Changes:
  • Basic tier users can now access batch endpoints in demo environment
  • Production environment remains unchanged - Advanced tier or higher still required
  • Rate limits still apply based on user tier
This change enables developers to test batch order functionality without needing Advanced tier access in the demo environment.
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Aug 13, 2025
The error messages when an incorrect API signature is passed have been improved
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Aug 9, 2025
The OpenAPI specification for the Kalshi API is now available at https://docs.kalshi.com/openapi.yaml. This allows developers to easily generate client libraries and integrate with the API using OpenAPI-compatible tools.
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Aug 8, 2025
Added client_order_id field to orderbook delta WebSocket messages. This field appears only when you caused the orderbook change and contains the client_order_id of your order that triggered the delta.WebSocket Message Enhancement:
  • New field: client_order_id (string, optional)
  • Present only when the authenticated user’s order causes the orderbook change
  • Contains the client-provided order ID of the triggering order
See the WebSocket documentation for implementation details.
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Aug 1, 2025
Added GET /portfolio/orders/queue_positions endpoint for retrieving queue positions of multiple resting orders.Request Parameters:
  • market_tickers (optional): Array of market tickers to filter by
  • event_ticker (optional): Event ticker to filter by
Note: You must specify one of market_tickers and event_ticker in the request.
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July 31, 2025
We are migrating our API documentation to a new platform:
  • RSS feed moved from https://trading-api.readme.io/changelog.rss to https://docs.kalshi.com/changelog/rss.xml
  • Documentation site trading-api.readme.io is now deprecated
  • New documentation home: https://docs.kalshi.com
  • Historical changelog entries will not be backfilled to the new RSS feed
Please update your bookmarks and RSS subscriptions.
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July 31, 2025
The GetEventMetadata endpoint has been expanded to include settlement sources.
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July 29, 2025
The GetApiVersion endpoint has been removed. API versioning will not be available for the time being.