---
title: OptimizelyConfigUpdate notification listener
slug: feature-experimentation/docs/optimizelyconfig-update-notification-listener
docTags: 
createdAt: 2026-08-05T20:39:55.000Z
---

Subscribe to the OptimizelyConfigUpdate notification listener to find out when the Feature Experimentation SDK's config manager has fetched an updated [datafile](docId:3LmHm4b3kTxKBuoR93KN8). You can use the notification to re-evaluate some or all of your flag rules to ensure that updates are reflected as as possible. The notification listener triggers on *any* datafile update. Datafile updates take place when there are any changes to the configuration or entities in the datafile's environment. For information, see [Get the datafile](docId:8_kRh18IHN_0bW1xf7jYv).

## Parameters

When the listener is triggered, the information provided is the output of `Get Optimizely Config`.  For information, see the following SDK documentation on OptimizelyConfig.

- [Android SDK](docId\:y-wqhSavcOcTN2ARyBfXV)
- [C# SDK](docId\:KPQCceg8F7-Wha2qGcRXJ)
- [Flutter SDK](docId\:NjbMIhrccsZsuckiJV-P3)
- [Go SDK](docId:8YevWRd8ThESsrWsF0ogT)
- [Java SDK](docId\:hLecDWvtv-VgcnlgYfelB)
- [JavaScript SDK](docId\:peAwVyvLK6ZSxsbszaiO6) – SDK versions 6.0.0 and later.
- [JavaScript (Browser) SDK](docId\:PDfRDsYl8Xx_0FJ_9unry) – SDK versions 5.3.5 and earlier.
- [JavaScript (Node) SDK](docId\:hKhtxowJe_Iz6e6f2QOZ-) – SDK versions 5.3.5 and earlier.
- [PHP SDK](docId\:wuEWpA9OAAJDRD7TPJx_v)
- [React SDK](docId\:jMtfFpSf8yrB_jWRR6fjS)
- [React Native SDK](docId\:LYQmx9F-32HbWEuBfkEig)
- [Ruby SDK](docId\:HzGY8snhn_pjldzRTct8V)
- [Python SDK](docId\:hyemSKdINH-zFg2-epg60)
- [Swift SDK](docId\:MIsKtFCm7XKiFkqzfe0BB)

## Examples

For code examples, see the following SDK documentation about notification listeners:

- [Android SDK](docId:7YBxDk67DRrkZf3FbyIJ-)
- [C# SDK](docId\:Ee1jEssfFPw17lJyVP9m9)
- [Flutter SDK](docId\:HK9-OAb_ZXtphGmvU8Uga)
- [Go SDK](docId\:t5MKaa3LIkBM5ovyv7XYn)
- [Java SDK](docId\:CaIM2oX09aWIajqNcz0Ct)
- [JavaScript SDK](docId\:iYEM6cOT51dak_I7ellNY) – SDK versions 6.0.0 and later.
- [JavaScript (Browser) SDK](docId\:qykXcla2WZgtq4LHGWSfU) – SDK versions 5.3.5 and earlier.
- [JavaScript (Node) SDK](docId\:qykXcla2WZgtq4LHGWSfU) – SDK versions 5.3.5 and earlier.
- [PHP SDK](docId\:B3h4PE4eFEjjhKpiue0N_)
- [React SDK](docId\:eyOn7CmG5jWwB3vIm7mt9)
- [React Native SDK](docId:04d5tm_qqBTXKMKKnh1rZ)
- [Ruby SDK](docId:0pKUE1RjpxrcY4xgjh1Y3)
- [Python SDK](docId\:EjbZOLZ2M6aN5QW0T1Ufy)
- [Swift SDK](docId\:olc5F0M6g6El8a0puGbRX)