langfuse · Steffen911 · Jul 23, 2026 · Jul 6, 2026 · Jul 13, 2026 · Jul 13, 2026
diff --git a/content/changelog/2025-12-17-v2-metrics-and-observations-api.mdx b/content/changelog/2025-12-17-v2-metrics-and-observations-api.mdx
@@ -17,7 +17,7 @@ We're releasing new **v2 endpoints** for our Metrics and Observations APIs, desi
 
 The v2 APIs are currently in **beta**. They are stable for production use, but some parameters and behaviors may evolve based on user feedback before general availability.
 
-**Cloud-only (Beta):** The v2 APIs are only available on Langfuse Cloud and currently in beta. We are working on a robust migration path for self-hosted deployments.
+**Availability:** The v2 APIs are available on Langfuse Cloud and on self-hosted deployments running [Langfuse v4](/self-hosting/upgrade/upgrade-guides/upgrade-v3-to-v4).
 
 **Important:** With current SDK versions, data may take approximately 5 minutes to appear on v2 endpoints. We will be releasing updated SDK versions soon that will make data available immediately on v2 endpoints.
 

diff --git a/content/changelog/2026-03-10-simplify-for-scale.mdx b/content/changelog/2026-03-10-simplify-for-scale.mdx
@@ -15,7 +15,7 @@ Langfuse is rolling out a simplified architecture built for significantly faster
 
 <Cards num={1}>
   <Card
-    title="Open the Fast Preview Docs"
+    title="Open the Langfuse v4 Docs"
     href="/docs/v4"
     icon={<ArrowRight />}
   />

diff --git a/content/changelog/2026-03-23-v4-dashboard-changes.mdx b/content/changelog/2026-03-23-v4-dashboard-changes.mdx
@@ -1,7 +1,7 @@
 ---
 date: 2026-03-23
 title: Updates to Dashboards
-description: Detailed reference for how dashboards behave differently in "Fast Preview" — trace counts, histograms, filters, and more.
+description: Detailed reference for how dashboards behave differently in Langfuse v4 — trace counts, histograms, filters, and more.
 ogImage: /images/changelog/2026-03-23-v4-dashboard-changes.jpg
 author: Valeriy
 canonical: /faq/all/dashboard-changes-in-v4

diff --git a/content/changelog/2026-04-13-experiments-rebuild.mdx b/content/changelog/2026-04-13-experiments-rebuild.mdx
@@ -15,7 +15,7 @@ Experiments are now a primary concept in Langfuse, sitting alongside Datasets ra
 While datasets are about **data**—curated collections of test cases you maintain and grow—experiments are about **execution**. They capture a specific run of your application against a set of inputs, freezing the results so you can compare them against past and future runs. Think of datasets as your reference material and experiments as the history of what you did with it.
 
 <Callout type="info">
-  This feature requires [Fast Preview mode](/docs/v4) to be enabled. Fast Preview is in open beta and currently available on Langfuse Cloud only—enable it in the bottom left of the UI to get started.
+  This feature requires [Langfuse v4](/docs/v4). On Langfuse Cloud, enable it via the toggle in the bottom left of the UI; on self-hosted deployments, [upgrade to Langfuse v4](/self-hosting/upgrade/upgrade-guides/upgrade-v3-to-v4) to get started.
 </Callout>
 
 ## Why this matters [#why-this-matters]

diff --git a/content/changelog/2026-06-19-filter-search-bar.mdx b/content/changelog/2026-06-19-filter-search-bar.mdx
@@ -20,10 +20,10 @@ level:ERROR type:TOOL environment:production latency:>2 name:*checkout*
 The **Filter Search Bar** turns one line of text into the same filters you would otherwise assemble in the sidebar, with autocomplete the whole way.
 
 <Callout type="info">
-  The Filter Search Bar runs on the Langfuse v4 data model. It is currently
-  available on Langfuse Cloud only; turn on **Fast** on the Observations or
-  Traces table to use it. Open-source support follows once the v4 schema
-  migration is ready for self-hosted deployments.
+  The Filter Search Bar runs on the [Langfuse v4](/docs/v4) data model. On
+  Langfuse Cloud, turn on **Fast** on the Observations or Traces table to use
+  it. On self-hosted deployments, it is available after [upgrading to Langfuse
+  v4](/self-hosting/upgrade/upgrade-guides/upgrade-v3-to-v4).
 </Callout>
 
 ## What you can type

diff --git a/content/docs/api-and-data-platform/features/export-to-blob-storage.mdx b/content/docs/api-and-data-platform/features/export-to-blob-storage.mdx
@@ -47,7 +47,7 @@ Exports can be written as Apache Parquet, CSV, JSON, or JSONL files. New integra
 
 Parquet observation exports do not include the per-unit model price columns (`input_price`, `output_price`, `total_price`). These columns snapshot model definition prices at export time and may be deprecated in the future — use `cost_details` and `total_cost` for cost data, which are included in every file type. See [Notes on Parquet exports](/docs/api-and-data-platform/features/blob-storage-export-fields#parquet-exports) in the field reference for details.
 
-## Export source (Fast Preview)
+## Export source (Langfuse v4)
 
 Blob Storage integrations now include an `Export Source` selector. New integrations default to `Enriched observations (recommended)` (trace attributes are directly set on observations).
 

diff --git a/content/docs/api-and-data-platform/features/observations-api.mdx b/content/docs/api-and-data-platform/features/observations-api.mdx
@@ -22,7 +22,7 @@ Older trace and observation read APIs remain available, but are not recommended
 
 <Callout type="warning">
 
-**Cloud-only:** The v2 Observations API is only available on Langfuse Cloud. We are working on a robust migration path for self-hosted deployments.
+**Availability:** The v2 Observations API is available on Langfuse Cloud and on self-hosted deployments running [Langfuse v4](/self-hosting/upgrade/upgrade-guides/upgrade-v3-to-v4).
 
 **Data availability:** Data from older SDKs (`langfuse-python` < `4.0.0`, `langfuse-js` < `5.0.0`) or direct OpenTelemetry exporters that do not send `x-langfuse-ingestion-version: 4` can be delayed by up to 10 minutes on v2 endpoints. Upgrade to [Python SDK v4.7.0+](/docs/observability/sdk/upgrade-path/python-v3-to-v4) or [JS/TS SDK v5.4.0+](/docs/observability/sdk/upgrade-path/js-v4-to-v5), or set that header on your OTEL span exporter, to see new data in real time.
 

diff --git a/content/docs/evaluation/evaluation-methods/llm-as-a-judge.mdx b/content/docs/evaluation/evaluation-methods/llm-as-a-judge.mdx
@@ -417,7 +417,7 @@ If your observation-level evaluator isn't executing, see [Why is my observation-
 
 You can run observation-level LLM-as-a-Judge on historical data from the observations table. This is useful if you have already ingested production data and want to score matching observations retroactively with a new or updated evaluator.
 
-**Prerequisite**: Enable the **[Fast Mode](/docs/v4)** toggle for the evaluator. To use the same evaluator on newly ingested data in real time, either upgrade to the latest SDKs (Python v4+ or JS/TS v5+) or, if you ingest directly via OTEL, set `x-langfuse-ingestion-version: 4` on your OTEL span exporter.
+**Prerequisite**: The evaluator must run on [Langfuse v4](/docs/v4) — on Langfuse Cloud, enable the **Fast Mode** toggle for the evaluator. To use the same evaluator on newly ingested data in real time, either upgrade to the latest SDKs (Python v4+ or JS/TS v5+) or, if you ingest directly via OTEL, set `x-langfuse-ingestion-version: 4` on your OTEL span exporter.
 
 To backfill scores:
 

diff --git a/content/docs/metrics/features/custom-dashboards.mdx b/content/docs/metrics/features/custom-dashboards.mdx
@@ -13,7 +13,7 @@ Custom dashboards provide a flexible, self-service analytics solution built on a
 Whether you're monitoring production performance, analyzing user feedback trends, or correlating costs with quality metrics, dashboards give you the visualization tools to make data-driven decisions.
 
 <Callout type="info">
-On [Fast Preview](/docs/v4), some dashboard behaviors are slightly updated. See [Dashboard changes in Fast Preview](/faq/all/dashboard-changes-in-v4) for the full reference.
+On [Langfuse v4](/docs/v4), some dashboard behaviors are slightly updated. See [Dashboard changes in Langfuse v4](/faq/all/dashboard-changes-in-v4) for the full reference.
 </Callout>
 
 <iframe

diff --git a/content/docs/metrics/features/metrics-api.mdx b/content/docs/metrics/features/metrics-api.mdx
@@ -23,7 +23,7 @@ The older Metrics API remains available, but is not recommended as the default f
 
 <Callout type="warning">
 
-**Cloud-only:** The v2 Metrics API is only available on Langfuse Cloud. We are working on a robust migration path for self-hosted deployments.
+**Availability:** The v2 Metrics API is available on Langfuse Cloud and on self-hosted deployments running [Langfuse v4](/self-hosting/upgrade/upgrade-guides/upgrade-v3-to-v4).
 
 **Data availability:** Data from older SDKs (`langfuse-python` < `4.0.0`, `langfuse-js` < `5.0.0`) or direct OpenTelemetry exporters that do not send `x-langfuse-ingestion-version: 4` can be delayed by up to 10 minutes on v2 endpoints. Upgrade to [Python SDK v4.7.0+](/docs/observability/sdk/upgrade-path/python-v3-to-v4) or [JS/TS SDK v5.4.0+](/docs/observability/sdk/upgrade-path/js-v4-to-v5), or set that header on your OTEL span exporter, to see new data in real time.
 

diff --git a/content/docs/observability/features/filter-search-bar.mdx b/content/docs/observability/features/filter-search-bar.mdx
@@ -13,10 +13,10 @@ level:ERROR type:TOOL environment:production latency:>2 name:*checkout*
 ```
 
 <Callout type="info">
-  The Filter Search Bar runs on the Langfuse v4 data model and is currently
-  available on Langfuse Cloud. Turn on **Fast** on the Observations or Traces
-  table to use it. Open-source support follows once the v4 schema migration is
-  ready for self-hosted deployments.
+  The Filter Search Bar runs on the [Langfuse v4](/docs/v4) data model. On
+  Langfuse Cloud, turn on **Fast** on the Observations or Traces table to use
+  it. On self-hosted deployments, it is available after [upgrading to Langfuse
+  v4](/self-hosting/upgrade/upgrade-guides/upgrade-v3-to-v4).
 </Callout>
 
 The bar runs next to the existing filter sidebar and time-range selector. Because the bar and the sidebar are two editors over the same filter state, anything you type appears as sidebar filters and vice versa. Type a field name and autocomplete suggests operators and observed values; press Enter to apply.

diff --git a/content/docs/v4.mdx b/content/docs/v4.mdx
@@ -1,18 +1,26 @@
 ---
-title: "Langfuse Fast Preview: Faster and Observations-First"
-description: Langfuse "Fast Preview" delivers faster performance and introduces an observations-first data model. Enable the preview and upgrade SDKs to get started.
+title: "Langfuse v4: Faster and Observations-First"
+description: Langfuse v4 delivers faster performance and introduces an observations-first data model. Available on Langfuse Cloud and for self-hosted deployments.
 ---
 
 import {
   BarChart3,
   Book,
   Github,
   LayoutDashboard,
+  Server,
   Table,
   Zap,
 } from "lucide-react";
 
-# Langfuse Cloud: Fast Preview
+# Langfuse v4
+
+<Callout type="info">
+  Langfuse v4 rolled out on Langfuse Cloud under the name **"Fast Preview"** —
+  the "Preview" and "Fast" toggles in the UI refer to this release. Fast
+  Preview _is_ Langfuse v4, and it is available both on Langfuse Cloud and for
+  [self-hosted deployments](/self-hosting/upgrade/upgrade-guides/upgrade-v3-to-v4).
+</Callout>
 
 ## At a glance
 
@@ -24,7 +32,8 @@ Langfuse is now observations-first. Queries that used to require expensive joins
 
 - **SDK:** Upgrade to [Python SDK v4.7.0+](/docs/observability/sdk/upgrade-path/python-v3-to-v4) / [JS/TS SDK v5.4.0+](/docs/observability/sdk/upgrade-path/js-v4-to-v5). Replace trace update calls with `propagate_attributes()`.
 - **OTEL:** Set the `x-langfuse-ingestion-version: 4` HTTP header on your span exporter. Propagate trace attributes to _all_ observations. [See setup guide](/integrations/native/opentelemetry)
-- **UI:** If your organization was created before April 14, 2026, 14:00 UTC (15:00 CET), enable the **Preview** toggle (bottom-left) to opt in. Organizations created on/after this cutoff are already on "Fast Preview" and do not see the toggle. Filter observations directly in the new unified table and create saved views for productive defaults. [See saved views guide](/faq/all/explore-observations-in-v4)
+- **UI (Langfuse Cloud):** If your organization was created before April 14, 2026, 14:00 UTC (15:00 CET), enable the **Preview** toggle (bottom-left) to opt in. Organizations created on/after this cutoff are already on Langfuse v4 and do not see the toggle. Filter observations directly in the new unified table and create saved views for productive defaults. [See saved views guide](/faq/all/explore-observations-in-v4)
+- **Self-hosting:** Upgrade your deployment to Langfuse v4 following the [v3 to v4 migration guide](/self-hosting/upgrade/upgrade-guides/upgrade-v3-to-v4).
 - **Evals:** Migrate LLM-as-a-Judge evals to the observation level. [See evals migration guide](/faq/all/llm-as-a-judge-migration)
 
 ---
@@ -33,7 +42,7 @@ Langfuse is now observations-first. Queries that used to require expensive joins
 
 Langfuse now delivers faster product performance at scale. Chart loading is much shorter, and browsing traces, users, and sessions is faster. The new Observations API v2 and Metrics API v2 query faster at scale. Observation-level evaluations now execute in seconds without a ClickHouse query per evaluation.
 
-We will keep this page updated as we roll out additional related features and share OSS and self-hosted support updates.
+Langfuse v4 is available on Langfuse Cloud and for [self-hosted deployments](/self-hosting/upgrade/upgrade-guides/upgrade-v3-to-v4). We will keep this page updated as we roll out additional related features.
 
 <Callout type="info">
   This version of Langfuse (v4) introduces a **single unified observations table** where all inputs,
@@ -54,15 +63,15 @@ As agentic applications grow more complex, a single trace can contain hundreds o
   />
 </Cards>
 
-## Preview access and rollout timeline
+## Rollout on Langfuse Cloud [#rollout]
 
-| Organization creation date (Langfuse Cloud)    | Fast Preview default | "Preview" toggle visibility      |
-| ---------------------------------------------- | -------------------- | -------------------------------- |
-| Before April 14, 2026, 14:00 UTC (15:00 CET)   | Optional             | Visible (you can switch on/off)  |
-| On/after April 14, 2026, 14:00 UTC (15:00 CET) | Enabled by default   | Hidden (already on Fast Preview) |
+| Organization creation date (Langfuse Cloud)    | Langfuse v4 default | "Preview" toggle visibility     |
+| ---------------------------------------------- | ------------------- | ------------------------------- |
+| Before April 14, 2026, 14:00 UTC (15:00 CET)   | Optional            | Visible (you can switch on/off) |
+| On/after April 14, 2026, 14:00 UTC (15:00 CET) | Enabled by default  | Hidden (already on v4)          |
 
 If you signed up recently and do not see the toggle, your organization is already on the new experience by default.
-For organizations created before the cutoff date, the "Preview" toggle is available in the bottom-left corner of the UI to opt in to "Fast Preview".
+For organizations created before the cutoff date, the "Preview" toggle is available in the bottom-left corner of the UI to opt in to Langfuse v4.
 
 <Frame className="max-w-xs mx-auto">
   ![Beta toggle in Langfuse
@@ -77,11 +86,11 @@ The toggle remains reversible for organizations created before the cutoff date.
 Data from SDKs `langfuse-js` < `5.0.0`, `langfuse-python` < `4.0.0`, or direct OpenTelemetry exporters that do not send `x-langfuse-ingestion-version: 4` can be delayed by up to 10 minutes in the new UI. Upgrade to the latest SDKs or set that header on your OTEL span exporter to see new data in real time.
 </Callout>
 
-### Migrate to the new experience
+## Migrate to the new experience
 
 <Steps>
 
-### Use a compatible ingestion path
+### Use a compatible ingestion path [#upgrade-sdks]
 
 To take advantage of the new data model and explore your data in real time, use one of these ingestion paths:
 
@@ -130,7 +139,7 @@ Observation-level evaluators only use data on the observation they run against.
   overview](/images/changelog/2026-03-10-v4-preview/data-model.png)
 </Frame>
 
-This preview is powered by a simplified observation-centric data model. Trace-level attributes such as `user_id`, `session_id`, and `metadata` now propagate automatically to observations, which helps remove expensive joins and keep the product fast at larger scale. Learn more in the [data model docs](/docs/observability/data-model) and [Explore Observations](/faq/all/explore-observations-in-v4).
+Langfuse v4 is powered by a simplified observation-centric data model. Trace-level attributes such as `user_id`, `session_id`, and `metadata` now propagate automatically to observations, which helps remove expensive joins and keep the product fast at larger scale. Learn more in the [data model docs](/docs/observability/data-model) and [Explore Observations](/faq/all/explore-observations-in-v4).
 
 ### What changes
 
@@ -143,11 +152,11 @@ This preview is powered by a simplified observation-centric data model. Trace-le
 
 ## OSS and self-hosting
 
-This preview is currently available on Langfuse Cloud. We are working on the migration path for OSS deployments and will share updates here, in the [changelog](/changelog), and in the dedicated [GitHub Discussion](https://github.com/orgs/langfuse/discussions/12518) as they become available.
+Langfuse v4 is available for self-hosted deployments. Follow the [v3 to v4 upgrade guide](/self-hosting/upgrade/upgrade-guides/upgrade-v3-to-v4) to migrate an existing deployment — the migration runs in independent steps and lets you retain v3 behavior until you complete the cutover on your own schedule. New deployments get the v4 defaults out of the box.
 
-## Questions on "Fast Preview"?
+## Questions on Langfuse v4?
 
-If you have questions about the rollout, migration steps, SDK upgrades, or anything unclear in the new experience, please ask them in the dedicated [GitHub Discussion](https://github.com/orgs/langfuse/discussions/12518). We will use that thread for rollout updates and answers.
+If you have questions about the rollout, migration steps, SDK upgrades, or anything unclear in the new experience, please ask them in the [v4 rollout GitHub Discussion](https://github.com/orgs/langfuse/discussions/14157). Background on the architecture change is collected in the [announcement discussion](https://github.com/orgs/langfuse/discussions/12518).
 
 ## Get started
 
@@ -173,13 +182,18 @@ If you have questions about the rollout, migration steps, SDK upgrades, or anyth
     icon={<BarChart3 />}
   />
   <Card
-    title="Dashboard Changes in Fast Preview"
+    title="Dashboard Changes in Langfuse v4"
     href="/faq/all/dashboard-changes-in-v4"
     icon={<LayoutDashboard />}
   />
   <Card
-    title="Ask Questions on Fast Preview"
-    href="https://github.com/orgs/langfuse/discussions/12518"
+    title="Self-Hosted Upgrade Guide"
+    href="/self-hosting/upgrade/upgrade-guides/upgrade-v3-to-v4"
+    icon={<Server />}
+  />
+  <Card
+    title="Ask Questions on Langfuse v4"
+    href="https://github.com/orgs/langfuse/discussions/14157"
     icon={<Github />}
   />
 </Cards>