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Changelog

Changes to the Arrow Trading API, the SDKs and these docs, newest first. Dates are when a change was published in the docs.

Breaking needs a change in your code   New new capability   Changed different behaviour or limits   Fixed the docs were wrong   Docs documentation only

October 2026

12 October

  • Fixed Error responses are documented as the API returns them: "status": "failure" with a numeric errorCode equal to the HTTP status. Response structure, Error codes
  • Fixed The Symbols field reference now matches the instrument CSV: all 25 columns, a table mapping CSV segments to API exchange codes, and a note that NSECO and NSECD are data only.
  • Fixed Instrument tokens in the Python SDK examples were labelled with the wrong symbols (3045 is SBIN, 2885 is RELIANCE). WebSocket streaming
  • Fixed triggerPrice is listed in the place and modify order parameters. Orders
  • Docs llms-full.txt follows the site's reading order, and llms.txt lists the WebSocket streams in their own section.

September 2026

29 September

  • New Interactive checksum generator and HFT packet decoder. Both run entirely in your browser.
  • Docs Redesigned homepage and doc pages, with light and dark themes. Code tabs now switch language together across a page.

23 September

  • Changed Python SDK: connect() is asynchronous, so subscribe to the data and HFT streams from the on_connect callback, not on the line after connecting. WebSocket streaming
  • Docs Every page can be copied or viewed as Markdown, for use with AI coding tools.

16 September

  • Docs CAS packet fields are now listed with their exact wire types (for example, prices are uint64). HFT stream

August 2026

31 August

  • New Official Go SDK documentation for github.com/arrow-trade/go-arrow, current release v1.8.0.
  • Breaking Refresh tokens are not supported. When an access token expires, log in again. The Go SDK no longer has GetRefreshToken or Config.RefreshToken. Authentication

27 August

  • Docs The order-updates WebSocket is documented as push-only: no subscription is needed, fills arrive as ORDER_UPDATE messages with reportType: "Fill", and position changes are not sent on this stream. Order updates

21 August

  • New HFT stream: after 3:20 PM IST, index symbols carry the indicative equilibrium price (IEP) in the ltp field of their ltpc and full packets. Index symbols cannot be subscribed in cas mode.

19 August

  • New cas mode on the HFT stream: 168-byte closing-auction packets with four price levels, imbalance and indicative price. HFT stream
  • Changed The HFT limit of 1,024 active symbols now applies per trading account across all HFT connections, not per connection. A single request can still include up to 512 symbols.

12 August

  • New Data Stream: from 3:15 PM IST every mode carries 16 extra bytes of closing-auction data (imbalance_qty, indicative_close, ref_price), so packets grow from 13/17/93/249 to 29/33/109/265 bytes. Market data

7 August

  • Fixed The redirect checksum is SHA-256 of checksumID:appID:request-token. The docs previously gave a different formula. Authentication

July 2026

27 July

  • New MCX futures and options (MCXFO) for orders, margin, quotes and streaming.

8 July

  • Breaking zstd compression became mandatory on the HFT stream. Connect with zstd=1 and decompress every inbound message before parsing; current pyarrow-client releases do this for you. HFT stream

1 July

  • Changed HFT subscription limits: up to 1,024 symbols (previously 500) and up to 512 symbols per request (previously 4,096).
  • Changed The zstd deadline moved from 1 July to 8 July 2026.
  • Fixed Modify order is PATCH /order/regular/{orderID}. The docs previously showed POST. Orders

June 2026

25 June

  • Docs Futures volume on the HFT stream (built from tick-by-tick data) is often lower than on the Data Stream (built from broadcast data), which can include spread-order-book activity.

22 June

  • New zstd compression on the HFT stream with zstd=1, announced as mandatory from 1 July 2026.

4 June

  • Fixed The Data Stream full packet is 249 bytes, with 8 reserved bytes before the market depth. The docs previously said 241. Market data

May 2026

18 May

  • Changed Order remarks are limited to 16 characters.

14 May

8 May

  • Breaking Plain market (MKT) orders are disabled by default on the API. Set mpp to send a limit order at the upper limit or DPR boundary for market-style execution. Orders

6 May

  • New Utility endpoints: holidays, index list, option chain symbols, option chain and Greeks.

April 2026

13 April

  • New Python SDK: HFT stream support through HFTDataStream.

11 April

  • Breaking HFT full packet grew from 192 to 196 bytes: open interest became a uint64 at offset 172, moving the server timestamp to offset 180. HFT stream

4 April

  • Breaking The Python SDK is imported as pyarrow_client, not pyarrow, to avoid clashing with Apache Arrow's pyarrow package. Install it with pip install pyarrow-client.

March 2026

13 March

January 2026

5 January