What is the IBKR TWS API message rate limit?

The client may send at most 50 messages per second to TWS. Each ticker subscription and cancellation counts as one message. Exceeding the sustained rate eventually causes TWS to close the connection.

What triggers an IBKR historical-data pacing violation?

Any of: more than 60 historical requests in a 10-minute window; 6 or more requests for the same contract, exchange, and tick type within 2 seconds; or an identical request repeated within 15 seconds. BID_ASK requests count double, and you may have at most 50 simultaneous open historical requests.

How do I poll IBKR option chains without hitting rate limits?

Use reqSecDefOptParams, which returns the full list of expirations and strikes for an underlying without the throttling limitation. The older reqContractDetails approach is throttled and slows down with ambiguous contract definitions.

How many instruments can IBKR stream at once?

100 market-data lines by default, with a minimum of 100. Streaming more than 100 symbols concurrently requires additional lines, which scale with commission activity.

IBKR TWS API Rate Limits 2026

The IBKR TWS API enforces a hard ceiling of 50 messages per second from client to TWS, plus a separate historical-data pacing regime: no more than 60 historical requests per 10-minute window, no 6+ identical-contract requests within 2 seconds, and no identical request repeated within 15 seconds. All of this is verified against the official TWS API docs on 2026-05-25¹². Breaching the message rate eventually drops your connection; breaching historical pacing returns a pacing-violation error. Option chains have a specific gotcha: the old contract-details method is throttled, but reqSecDefOptParams is not³. This is the operational spec you build a resilient IBKR client against. Map it against other brokers in the Broker API Comparator.

TL;DR

Global message rate: 50 messages/second from client to TWS; over-limit eventually closes the connection¹.
Historical-data pacing (each is a violation)²:
- More than 60 historical requests in any 10-minute period.
- 6+ historical requests for the same contract, exchange, and tick type within 2 seconds.
- An identical historical request repeated within 15 seconds.
- BID_ASK requests count double.
Max open historical requests: 50 simultaneous².
Market-data lines: 100 by default (minimum 100)².
Option chains: reqContractDetails is throttled; reqSecDefOptParams avoids the throttle³.

The global message rate

Every other rule sits on top of one ceiling: the client may send at most 50 messages per second to TWS¹. Each ticker subscription request and each cancellation counts as one message. This is not a per-minute budget you can burst into; it is a sustained-rate cap. Sustained breaches do not return a clean 429 — TWS eventually closes the socket¹. The correct client design paces all outbound traffic under 50/second with a token bucket, treating subscriptions, orders, and data requests as drawing from the same per-second budget.

Historical-data pacing rules

Historical data has its own pacing layer, because backfilling bars is the easiest way to flood the gateway. A pacing violation is triggered by any of these²:

Rule	Threshold
Requests per 10-minute window	More than 60
Same contract/exchange/tick type	6+ within 2 seconds
Identical request repeated	Within 15 seconds
BID_ASK requests	Count double toward all limits
Max simultaneous open requests	50

All verified on 2026-05-25². The practical reading: when backfilling a universe, stagger requests so you stay under 6 per contract per 2 seconds and under 60 total per 10 minutes, and never re-fire an identical request inside 15 seconds. A queue with a per-10-minute counter and a per-contract debounce is the standard pattern.

What a pacing violation looks like

When you cross a historical-data threshold, TWS returns a pacing-violation error rather than silently dropping data. Recovery is to pause, let the 10-minute window roll, and resume at a slower cadence. Unlike the 50/second message limit (which can kill the connection), a historical pacing violation is recoverable in place — but it stalls your backfill, so prevention beats recovery.

The option-chain gotcha

Polling option chains is where many IBKR integrations accidentally trip pacing. The older approach of enumerating contracts via reqContractDetails is throttled — the more ambiguous the contract definition, the slower and more rate-limited the return³. The fix is the dedicated method: reqSecDefOptParams returns the full list of expirations and strikes for an underlying without the throttling limitation³. For any option-chain workload, use reqSecDefOptParams; reserve reqContractDetails for narrow, fully-specified lookups.

Market-data lines

Separate from pacing, IBKR limits how many instruments you can stream concurrently: 100 market-data lines by default, with a minimum of 100². Streaming quotes on more than 100 symbols at once requires more lines (which scale with commission activity). A scanner watching a broad universe should rotate subscriptions through the line budget rather than assuming unlimited concurrent streams.

Building a compliant client

One token bucket at 50/second for all outbound messages: the master constraint.
Historical queue with a 10-minute rolling counter (cap 60), a per-contract 2-second debounce, and a 15-second identical-request guard.
Use reqSecDefOptParams for option chains, never reqContractDetails in a loop.
Rotate market-data subscriptions through the 100-line budget.
Treat the 50/second limit as connection-fatal and historical pacing as recoverable-but-stalling.

For the cost side of IBKR (the API is free; you pay commissions and per-exchange data), see Interactive Brokers API Pricing 2026.

Verified figures

The 50 messages/second client limit, the historical-data pacing thresholds (60/10min, 6/2s, 15s identical, BID_ASK double, 50 max open), the 100 default market-data lines, and the reqSecDefOptParams throttle exemption were all verified against the official TWS API documentation on 2026-05-25.

Connects to

Interactive Brokers API Pricing 2026: the cost side of the same API.
Alpaca vs Interactive Brokers API 2026: pacing model versus a flat per-minute cap.
Choosing a Broker API in 2026: the five-broker pillar.
Broker API Comparator: rate models side by side.

References

Interactive Brokers. "TWS API - Introduction" (TWS accepts up to fifty messages per second from the client side; over-limit closes the connection; each subscription/cancellation is one message). interactivebrokers.github.io, verified 2026-05-25. https://interactivebrokers.github.io/tws-api/introduction.html ↩ ↩² ↩³ ↩⁴
Interactive Brokers. "TWS API - Historical Data Limitations" (60 requests / 10 minutes, 6 same-contract requests / 2 seconds, identical request within 15 seconds, BID_ASK counts double, 50 max simultaneous open requests). verified 2026-05-25. https://interactivebrokers.github.io/tws-api/historical_limitations.html ↩ ↩² ↩³ ↩⁴ ↩⁵ ↩⁶ ↩⁷
Interactive Brokers. "TWS API - Options" (reqSecDefOptParams returns expirations and strikes without the reqContractDetails throttling limitation). verified 2026-05-25. https://interactivebrokers.github.io/tws-api/options.html ↩ ↩² ↩³ ↩⁴

Verified engine output

Show the recompute-verified inputs and outputs

Multi-asset brokers including futures coverage

Inputs
require_futures	1
max_auth_complexity	5

Result
filters › require options	false
filters › require futures	true
filters › require crypto	false
filters › require mcp	false
filters › require free tier	false
filters › max auth complexity	5
results › row 1 › broker › id	schwab
results › row 1 › broker › name	Schwab
results › row 1 › broker › url	https://www.schwab.com/
results › row 1 › broker › docs url	https://developer.schwab.com/
results › row 1 › broker › auth	OAuth 2.0 (3-legged)
results › row 1 › broker › auth complexity	4
results › row 1 › broker › order types (9 items)	[...]
results › row 1 › broker › rate limits	120 req/min per endpoint (published tier)
results › row 1 › broker › market data › row 1	Real-time equities + options quotes
results › row 1 › broker › market data › row 2	Historical bars (1m to daily)
results › row 1 › broker › market data › row 3	No exchange depth via API
results › row 1 › broker › mcp	none
results › row 1 › broker › mcp note	No official or listed community MCP server
results › row 1 › broker › assets › stocks	true
results › row 1 › broker › assets › options	true
results › row 1 › broker › assets › futures	true
results › row 1 › broker › assets › crypto	false
results › row 1 › broker › assets › forex	true
results › row 1 › broker › assets › bonds	true
results › row 1 › broker › account minimum	0
results › row 1 › broker › commission	$0 equities, $0.65/contract options
results › row 1 › broker › good for	Established retail, post-TDA API migration
results › row 1 › broker › has free tier	true
results › row 1 › broker › notes › row 1	API rebuilt after TD Ameritrade integration; still maturing
results › row 1 › broker › notes › row 2	Requires individual developer registration and app review
results › row 1 › broker › notes › row 3	Token refresh flow is finicky vs Alpaca/Tradier
results › row 1 › score	2
results › row 1 › max score	2
results › row 1 › fits	true
results › row 2 › broker › id	ibkr
results › row 2 › broker › name	Interactive Brokers
results › row 2 › broker › url	https://www.interactivebrokers.com/
results › row 2 › broker › docs url	https://www.interactivebrokers.com/en/trading/ib-api.php
results › row 2 › broker › auth	OAuth + TWS/IB Gateway
results › row 2 › broker › auth complexity	5
results › row 2 › broker › order types (10 items)	[...]
results › row 2 › broker › rate limits	~50 msg/sec per connection; 50 orders/sec burst
results › row 2 › broker › market data › row 1	Global equities via subscription bundles
results › row 2 › broker › market data › row 2	Level-2 depth on most exchanges
results › row 2 › broker › market data › row 3	Historical depth across asset classes
results › row 2 › broker › mcp	community
results › row 2 › broker › mcp note	Community CLI MCP; audit before production
results › row 2 › broker › assets › stocks	true
results › row 2 › broker › assets › options	true
results › row 2 › broker › assets › futures	true
results › row 2 › broker › assets › crypto	true
results › row 2 › broker › assets › forex	true
results › row 2 › broker › assets › bonds	true
results › row 2 › broker › account minimum	0
results › row 2 › broker › commission	Tiered per-share or fixed; ~$0.0035/sh tiered
results › row 2 › broker › good for	Multi-asset-class, international, scale
results › row 2 › broker › has free tier	false
results › row 2 › broker › notes › row 1	Requires TWS or IB Gateway running locally
results › row 2 › broker › notes › row 2	Idempotency via client-supplied orderId
results › row 2 › broker › notes › row 3	Fully headless gateway is possible but under-documented
results › row 2 › score	2
results › row 2 › max score	2
results › row 2 › fits	true
results › row 3 › broker › id	alpaca
results › row 3 › broker › name	Alpaca
results › row 3 › broker › url	https://alpaca.markets/
results › row 3 › broker › docs url	https://alpaca.markets/docs/
results › row 3 › broker › auth	API Key + Secret
results › row 3 › broker › auth complexity	1
results › row 3 › broker › order types (10 items)	[...]
results › row 3 › broker › rate limits	200 req/min (free), higher on paid tiers
results › row 3 › broker › market data › row 1	IEX real-time (free)
results › row 3 › broker › market data › row 2	Full SIP on Algo Trader Plus ($99/mo)
results › row 3 › broker › market data › row 3	Historical bars + trades + quotes
results › row 3 › broker › mcp	official
results › row 3 › broker › mcp note	Official MCP V2, 61 actions, idempotent order submission
results › row 3 › broker › assets › stocks	true
results › row 3 › broker › assets › options	true
results › row 3 › broker › assets › futures	false
results › row 3 › broker › assets › crypto	true
results › row 3 › broker › assets › forex	false
results › row 3 › broker › assets › bonds	false
results › row 3 › broker › account minimum	0
results › row 3 › broker › commission	$0 (PFOF on equities)
results › row 3 › broker › good for	Solo AI operator, paper-to-live parity
results › row 3 › broker › has free tier	true
results › row 3 › broker › notes › row 1	Free paper trading with same API surface as live
results › row 3 › broker › notes › row 2	Options require Algo Trader Plus tier
results › row 3 › broker › notes › row 3	Python/Go SDKs mature; rate-limit backoff documented
results › row 3 › score	1
results › row 3 › max score	2
results › row 3 › fits	false
results › row 3 › fail reasons › row 1	Futures
results › row 4 › broker › id	tradier
results › row 4 › broker › name	Tradier
results › row 4 › broker › url	https://tradier.com/
results › row 4 › broker › docs url	https://developer.tradier.com/
results › row 4 › broker › auth	OAuth 2.0
results › row 4 › broker › auth complexity	3
results › row 4 › broker › order types (8 items)	[...]
results › row 4 › broker › rate limits	120 req/min market data, 60 req/min trading
results › row 4 › broker › market data › row 1	Real-time equities + options (streaming)
results › row 4 › broker › market data › row 2	Historical OHLC back ~5 years
results › row 4 › broker › market data › row 3	No Level-2 depth
results › row 4 › broker › mcp	community
results › row 4 › broker › mcp note	Community MCP; idempotency is a manual patch
results › row 4 › broker › assets › stocks	true
results › row 4 › broker › assets › options	true
results › row 4 › broker › assets › futures	false
results › row 4 › broker › assets › crypto	false
results › row 4 › broker › assets › forex	false
results › row 4 › broker › assets › bonds	false
results › row 4 › broker › account minimum	0
results › row 4 › broker › commission	$0 equities (PFOF), $0.35/contract options Pro
results › row 4 › broker › good for	Options-first retail, multi-leg strategies
results › row 4 › broker › has free tier	true
results › row 4 › broker › notes › row 1	Free sandbox with delayed data
results › row 4 › broker › notes › row 2	Strong options chain + multi-leg order API
results › row 4 › broker › notes › row 3	US-only account eligibility
results › row 4 › score	1
results › row 4 › max score	2
results › row 4 › fits	false
results › row 4 › fail reasons › row 1	Futures
results › row 5 › broker › id	robinhood
results › row 5 › broker › name	Robinhood
results › row 5 › broker › url	https://robinhood.com/
results › row 5 › broker › docs url	https://docs.robinhood.com/
results › row 5 › broker › auth	OAuth 2.0 (unofficial endpoints)
results › row 5 › broker › auth complexity	4
results › row 5 › broker › order types › row 1	market
results › row 5 › broker › order types › row 2	limit
results › row 5 › broker › order types › row 3	stop
results › row 5 › broker › order types › row 4	stop-limit
results › row 5 › broker › order types › row 5	gtc
results › row 5 › broker › order types › row 6	ioc
results › row 5 › broker › rate limits	Not publicly documented; low throughput
results › row 5 › broker › market data › row 1	Delayed quotes in public tier
results › row 5 › broker › market data › row 2	Limited historical depth
results › row 5 › broker › market data › row 3	No public Level-2
results › row 5 › broker › mcp	none
results › row 5 › broker › mcp note	No MCP; unofficial SDKs only
results › row 5 › broker › assets › stocks	true
results › row 5 › broker › assets › options	true
results › row 5 › broker › assets › futures	false
results › row 5 › broker › assets › crypto	true
results › row 5 › broker › assets › forex	false
results › row 5 › broker › assets › bonds	false
results › row 5 › broker › account minimum	0
results › row 5 › broker › commission	$0 (PFOF), $5/mo Gold for margin + extras
results › row 5 › broker › good for	Casual retail; not recommended for agents
results › row 5 › broker › has free tier	true
results › row 5 › broker › notes › row 1	No officially supported public API in 2026
results › row 5 › broker › notes › row 2	Community SDKs break on auth changes without notice
results › row 5 › broker › notes › row 3	Paper trading unavailable
results › row 5 › score	1
results › row 5 › max score	2
results › row 5 › fits	false
results › row 5 › fail reasons › row 1	Futures
fitting brokers › row 1 › broker › id	schwab
fitting brokers › row 1 › broker › name	Schwab
fitting brokers › row 1 › broker › url	https://www.schwab.com/
fitting brokers › row 1 › broker › docs url	https://developer.schwab.com/
fitting brokers › row 1 › broker › auth	OAuth 2.0 (3-legged)
fitting brokers › row 1 › broker › auth complexity	4
fitting brokers › row 1 › broker › order types (9 items)	[...]
fitting brokers › row 1 › broker › rate limits	120 req/min per endpoint (published tier)
fitting brokers › row 1 › broker › market data › row 1	Real-time equities + options quotes
fitting brokers › row 1 › broker › market data › row 2	Historical bars (1m to daily)
fitting brokers › row 1 › broker › market data › row 3	No exchange depth via API
fitting brokers › row 1 › broker › mcp	none
fitting brokers › row 1 › broker › mcp note	No official or listed community MCP server
fitting brokers › row 1 › broker › assets › stocks	true
fitting brokers › row 1 › broker › assets › options	true
fitting brokers › row 1 › broker › assets › futures	true
fitting brokers › row 1 › broker › assets › crypto	false
fitting brokers › row 1 › broker › assets › forex	true
fitting brokers › row 1 › broker › assets › bonds	true
fitting brokers › row 1 › broker › account minimum	0
fitting brokers › row 1 › broker › commission	$0 equities, $0.65/contract options
fitting brokers › row 1 › broker › good for	Established retail, post-TDA API migration
fitting brokers › row 1 › broker › has free tier	true
fitting brokers › row 1 › broker › notes › row 1	API rebuilt after TD Ameritrade integration; still maturing
fitting brokers › row 1 › broker › notes › row 2	Requires individual developer registration and app review
fitting brokers › row 1 › broker › notes › row 3	Token refresh flow is finicky vs Alpaca/Tradier
fitting brokers › row 1 › score	2
fitting brokers › row 1 › max score	2
fitting brokers › row 1 › fits	true
fitting brokers › row 2 › broker › id	ibkr
fitting brokers › row 2 › broker › name	Interactive Brokers
fitting brokers › row 2 › broker › url	https://www.interactivebrokers.com/
fitting brokers › row 2 › broker › docs url	https://www.interactivebrokers.com/en/trading/ib-api.php
fitting brokers › row 2 › broker › auth	OAuth + TWS/IB Gateway
fitting brokers › row 2 › broker › auth complexity	5
fitting brokers › row 2 › broker › order types (10 items)	[...]
fitting brokers › row 2 › broker › rate limits	~50 msg/sec per connection; 50 orders/sec burst
fitting brokers › row 2 › broker › market data › row 1	Global equities via subscription bundles
fitting brokers › row 2 › broker › market data › row 2	Level-2 depth on most exchanges
fitting brokers › row 2 › broker › market data › row 3	Historical depth across asset classes
fitting brokers › row 2 › broker › mcp	community
fitting brokers › row 2 › broker › mcp note	Community CLI MCP; audit before production
fitting brokers › row 2 › broker › assets › stocks	true
fitting brokers › row 2 › broker › assets › options	true
fitting brokers › row 2 › broker › assets › futures	true
fitting brokers › row 2 › broker › assets › crypto	true
fitting brokers › row 2 › broker › assets › forex	true
fitting brokers › row 2 › broker › assets › bonds	true
fitting brokers › row 2 › broker › account minimum	0
fitting brokers › row 2 › broker › commission	Tiered per-share or fixed; ~$0.0035/sh tiered
fitting brokers › row 2 › broker › good for	Multi-asset-class, international, scale
fitting brokers › row 2 › broker › has free tier	false
fitting brokers › row 2 › broker › notes › row 1	Requires TWS or IB Gateway running locally
fitting brokers › row 2 › broker › notes › row 2	Idempotency via client-supplied orderId
fitting brokers › row 2 › broker › notes › row 3	Fully headless gateway is possible but under-documented
fitting brokers › row 2 › score	2
fitting brokers › row 2 › max score	2
fitting brokers › row 2 › fits	true

Computed live at build time.

Frequently asked questions

What is the IBKR TWS API message rate limit?: The client may send at most 50 messages per second to TWS. Each ticker subscription and cancellation counts as one message. Exceeding the sustained rate eventually causes TWS to close the connection.
What triggers an IBKR historical-data pacing violation?: Any of: more than 60 historical requests in a 10-minute window; 6 or more requests for the same contract, exchange, and tick type within 2 seconds; or an identical request repeated within 15 seconds. BID_ASK requests count double, and you may have at most 50 simultaneous open historical requests.
How do I poll IBKR option chains without hitting rate limits?: Use reqSecDefOptParams, which returns the full list of expirations and strikes for an underlying without the throttling limitation. The older reqContractDetails approach is throttled and slows down with ambiguous contract definitions.
How many instruments can IBKR stream at once?: 100 market-data lines by default, with a minimum of 100. Streaming more than 100 symbols concurrently requires additional lines, which scale with commission activity.