Fyers API C SDK : fyers-api-c - v1.4.0

The official Fyers C SDK for API-V3 Users FYERS API.

Fyers API is a set of REST-like APIs that provide integration with our in-house trading platform with which you can build your own customized trading applications.

Documentation

• Fyers API documentation

Requirements

• CMake 3.15+
• C compiler (C11)
• Dependencies: libcurl, cJSON, OpenSSL, libwebsockets

Package	Linux (apt)	macOS (Homebrew)	Windows (vcpkg)
cmake	cmake	cmake	CMake installer
curl	libcurl4-openssl-dev	curl	curl
cJSON	libcjson-dev	cjson	cjson
OpenSSL	libssl-dev	openssl	openssl
libwebsockets	libwebsockets-dev	libwebsockets	libwebsockets

Getting the source

Clone the repository (or download and extract the source), then build from that directory:

git clone <repository-url> fyers-c-sdk
cd fyers-c-sdk

Replace <repository-url> with the actual repo URL. All build and install steps below are run from this SDK root directory.

Usage

Linux (Ubuntu/Debian)

Install dependencies and build:

sudo apt-get update
sudo apt-get install -y build-essential cmake \
    libcurl4-openssl-dev libcjson-dev libssl-dev libwebsockets-dev

mkdir build && cd build
cmake .. -DCMAKE_INSTALL_PREFIX=/usr/local
make
sudo make install
sudo ldconfig

macOS

brew install cmake curl cjson openssl libwebsockets

mkdir build && cd build
cmake .. -DCMAKE_INSTALL_PREFIX=/usr/local
make
sudo make install

Windows

1. Install Visual Studio (2019+) with "Desktop development with C++"
2. Install CMake
3. Install vcpkg and install dependencies for x64:

vcpkg install cjson:x64-windows curl:x64-windows openssl:x64-windows libwebsockets:x64-windows

4. Build (from the SDK root directory):

cmake -S . -B build -DCMAKE_TOOLCHAIN_FILE=C:\vcpkg\scripts\buildsystems\vcpkg.cmake -A x64
cmake --build build --config Release
cmake --install build --config Release --prefix C:\fyers-sdk

Use your actual vcpkg path if it is not C:\vcpkg. Add the install bin/ directory to your PATH, or copy fyers-api-c.dll next to your executable.

Link in Your Project

Direct compile (gcc/clang):

gcc main.c -lfyers-api-c -o myapp

CMake:

find_package(fyers-api-c REQUIRED)
add_executable(myapp main.c)
target_link_libraries(myapp PRIVATE fyers-api-c::fyers-api-c)

Include headers:

#include <fyers_api.h>
#include <fyers_model.h>
#include <fyers_session.h>
#include <fyers_data_ws.h>
#include <fyers_order_ws.h>

Quick Start

#include <fyers_api.h>
#include <fyers_session.h>
#include <fyers_model.h>

int main(void) {
    fyers_session_t* session = fyers_session_create(
        "YOUR_CLIENT_ID", "YOUR_REDIRECT_URI", "YOUR_SECRET_KEY"
    );
    generate_authcode(session);
    fyers_session_set_authcode(session, "AUTH_CODE_FROM_REDIRECT");
    generate_token(session);

    const char* client_id = fyers_session_get_client_id(session);
    const char* access_token = fyers_session_get_access_token(session);
    fyers_model_t* model = fyers_model_create(
        client_id, access_token, false, NULL, FYERS_LOG_INFO
    );

    fyers_response_t* response = fyers_model_get_profile(model);
    if (response && response->error == FYERS_OK)
        printf("Profile: %.*s\n", (int)response->size, response->data);
    fyers_response_destroy(response);

    fyers_model_destroy(model);
    fyers_session_destroy(session);
    fyers_cleanup();
    return 0;
}

Try running the sample code from the Fyers API documentation.

APIs Supported by Fyers C SDK

Authentication

• Generate Auth Code
• Generate Access Token
• Generate Token with Refresh Token

User

• Profile
• Funds
• Holdings
• Logout

Transaction Info

• Orders
• Positions
• Trades

Order Placement

• Place Order
• Place Multi Order
• Place Basket Orders
• Place MultiLeg Order

GTT Orders

• GTT Single
• GTT Modify Order
• GTT Cancel Order
• GTT Order Book

Smart Orders

• Smart Limit
• Smart Trail
• Smart Step
• Smart SIP
• Modify Smart Order
• Cancel Smart Order
• Pause Smart Order
• Resume Smart Order
• Smart Order Book

Smart Exit

• Create Smart Exit
• Fetch Smart Exit
• Modify / Activate / Deactivate Smart Exit

Other Transactions

• Modify Orders
• Modify Basket Orders
• Cancel Order
• Cancel Basket Orders
• Exit Position
• Exit All Positions
• Convert Position
• Attach Position Legs

Broker Config

• Market Status

Data Api

• History
• Quotes
• Market Depth
• Option Chain
• History Expiry Dates
• History Underlying Symbols
• History FNO Expired
• Futures Chain

Reports

• Order History
• Trade History
• Charges History
• Realised Profit
• Tax PnL History
• Ledger History

Price Alert

• Create Price Alert
• Get Price Alerts
• Modify Price Alert
• Delete Price Alert
• Enable/Disable Price Alert

TP/SL Smart Orders (BO/CO migration)

Product types BO and CO are deprecated and rejected by the API. Use standard products (CNC, INTRADAY, MARGIN, MTF) with offset-based TP/SL fields:

Field	Meaning
takeProfit	Profit target offset (not absolute price)
stopLoss	Stop loss offset
legType	1 = points (default), 2 = percent of entry

TP/SL is supported only on sync endpoints (/orders/sync, /multi-order/sync). Create the model with is_async = false. Orderbook and position responses may include takeProfit, stopLoss, and legType when legs are active.

/* Place order — TP/SL/legType omitted (not mandatory) */
fyers_model_place_order(model, order_json);

/* Optionally add any of takeProfit / stopLoss / legType */
cJSON_AddNumberToObject(json, "takeProfit", 10.5);
cJSON_AddNumberToObject(json, "stopLoss", 5.0);
cJSON_AddNumberToObject(json, "legType", FYERS_LEG_TYPE_POINTS); /* optional; defaults to 1 */
fyers_model_place_order(model, cJSON_Print(json));

/* Modify: update TP, remove SL (JSON null) */
cJSON_AddNumberToObject(mod, "takeProfit", 15.0);
cJSON_AddNullToObject(mod, "stopLoss");
fyers_model_modify_order(model, cJSON_PrintUnformatted(mod));

/* Attach legs to an open position */
cJSON_AddStringToObject(pos, "positionId", "NSE:SBIN-EQ-INTRADAY");
cJSON_AddNumberToObject(pos, "takeProfit", 2.5);
cJSON_AddNumberToObject(pos, "stopLoss", 1.5);
cJSON_AddNumberToObject(pos, "legType", FYERS_LEG_TYPE_PERCENT);
fyers_model_attach_position_legs(model, cJSON_PrintUnformatted(pos));

Expired F&O Historical Data

GET https://api-t1.fyers.in/data/history/fno/expired/expiry-dates?symbol=...&range_from=...&range_to=...&date_format=...

cJSON* json = cJSON_CreateObject();
cJSON_AddStringToObject(json, "symbol", "NSE:NIFTY50-INDEX");
cJSON_AddStringToObject(json, "range_from", "2024-01-01");
cJSON_AddStringToObject(json, "range_to", "2024-12-31");
cJSON_AddStringToObject(json, "date_format", "1");
char* params = cJSON_PrintUnformatted(json);
fyers_response_t* response = fyers_model_get_history_expiry_dates(model, params);

GET https://api-t1.fyers.in/data/history/fno/expired/underlying-symbols?symbol=...&expiry_date=...

cJSON* json = cJSON_CreateObject();
cJSON_AddStringToObject(json, "symbol", "NSE:NIFTY50-INDEX");
cJSON_AddStringToObject(json, "expiry_date", "2024-11-28");
char* params = cJSON_PrintUnformatted(json);
fyers_response_t* response = fyers_model_get_history_underlying_symbols(model, params);

GET https://api-t1.fyers.in/data/history/fno/expired/historical-data?symbol=...&resolution=...&date_format=...&range_from=...&range_to=...&include_greeks=...&include_oi=...

cJSON* json = cJSON_CreateObject();
cJSON_AddStringToObject(json, "symbol", "NSE:NIFTY24NOV22500CE");
cJSON_AddStringToObject(json, "resolution", "5");
cJSON_AddStringToObject(json, "date_format", "1");
cJSON_AddStringToObject(json, "range_from", "2024-11-01");
cJSON_AddStringToObject(json, "range_to", "2024-11-28");
cJSON_AddStringToObject(json, "include_greeks", "1");
cJSON_AddStringToObject(json, "include_oi", "1");
char* params = cJSON_PrintUnformatted(json);
fyers_response_t* response = fyers_model_get_history_fno_expired(model, params);

Futures Chain

GET https://api-t1.fyers.in/data/futures-chain?symbol=...

fyers_response_t* response = fyers_model_get_futures_chain(model, "NSE:NIFTY50-INDEX");
if (response && response->error == FYERS_OK)
    printf("Futures chain: %.*s\n", (int)response->size, response->data);
fyers_response_destroy(response);

Web Socket

General Socket

• General Socket (orders)
• General Socket (trades)
• General Socket (positions)
• General Socket (general)

Market Data

• Market Data Symbol Update
• Market Data Indices Update
• Market Data Depth Update
• Market Data Lite-Mode
• Market Data Unsubscribe
• Market Data Channel Resume

Supported Platforms

Platform	Library Output
macOS	libfyers-api-c.dylib
Linux	libfyers-api-c.so
Windows	fyers-api-c.dll + fyers-api-c.lib

Examples

Build with examples enabled:

cmake .. -DBUILD_EXAMPLES=ON
make

Examples are in build/examples/ (REST API, WebSocket data, WebSocket orders).

Troubleshooting

Issue	Fix
macOS: dyld: Library not loaded	Set DYLD_LIBRARY_PATH=/usr/local/lib or install to /usr/local
Linux: cannot open shared object file	Run sudo ldconfig or set LD_LIBRARY_PATH=/usr/local/lib
Windows: fyers-api-c.dll was not found	Add bin/ to PATH or copy DLL next to your executable
Missing dependencies	Linux: install -dev packages; macOS: Homebrew; Windows: vcpkg

Release Notes

• Cross-platform support (macOS, Linux, Windows)
• Shared library with proper symbol export for Windows DLL
• CMake package config for find_package(fyers-api-c)
• Smart Orders and Smart Exits API support
• TP/SL overlay on sync place/modify; fyers_model_attach_position_legs
• Reports APIs (order/trade/charges/PnL/ledger history)
• Expired F&O historical data (expiry dates, underlying symbols, FNO expired candles)
• Futures chain
• Refresh token exchange (generate_token_with_refresh_token)