chore: deprecate substrate-api-sidecar in favor of polkadot-rest-api (#1951)

* add deprecation message

* remove emojis & mention v1

* add startup log warning

* add deprecation note in changelog for next release

* add deprecation note in dockerfile readme

* update docs and docs-v2 with deprecation note

* update github issue templates with deprecation note

* update bifrost endpoint

* fix: removed CoretimeAssignmentProvider from requiredPallets
- CoretimeAssignmentProvider pallet was removed from the relay chain runtime in polkadot-sdk PR 10184

Author: Imod7

.github/ISSUE_TEMPLATE/feature-request.md

@@ -6,6 +6,12 @@ labels: Enhancement
 assignees: ""
 ---
 
+> ⚠️ **`substrate-api-sidecar` is deprecated** in favor of [`polkadot-rest-api`](https://github.com/paritytech/polkadot-rest-api), a Rust rewrite with 1:1 API compatibility. **New features will not be added to this repository.**
+>
+> Please file your feature request against [`polkadot-rest-api`](https://github.com/paritytech/polkadot-rest-api/issues/new/choose) instead — that's where new development is happening.
+>
+> Migration guide: https://github.com/paritytech/polkadot-rest-api/blob/main/docs/guides/MIGRATION.md
+
 **Proposed Change or Idea**
 
 [Describe your request for a new idea/feature or improvement of an existing

.github/ISSUE_TEMPLATE/report-bug.md

@@ -6,6 +6,12 @@ labels: ""
 assignees: ""
 ---
 
+> ⚠️ **`substrate-api-sidecar` is deprecated** in favor of [`polkadot-rest-api`](https://github.com/paritytech/polkadot-rest-api), a Rust rewrite with 1:1 API compatibility.
+>
+> **If possible, please reproduce against [`polkadot-rest-api`](https://github.com/paritytech/polkadot-rest-api) first** — if the bug exists there, file it [there](https://github.com/paritytech/polkadot-rest-api/issues/new/choose) so it's fixed in the actively-developed version.
+>
+> Migration guide: https://github.com/paritytech/polkadot-rest-api/blob/main/docs/guides/MIGRATION.md
+
 **Description**
 
 [Please add a clear description of the bug you are encountering, such as any

CHANGELOG.md

@@ -2,6 +2,21 @@
 
 All notable changes to this project will be documented in this file. See [standard-version](https://github.com/conventional-changelog/standard-version) for commit guidelines.
 
+## Unreleased
+
+### ⚠️ Deprecation Notice
+
+**`substrate-api-sidecar` is deprecated in favor of [`polkadot-rest-api`](https://github.com/paritytech/polkadot-rest-api).**
+
+`polkadot-rest-api` is a ground-up Rust rewrite built on [`subxt`](https://github.com/paritytech/subxt) with 1:1 API compatibility (endpoints served under `/v1/`, e.g. `/v1/blocks/head`), stable memory under sustained load, significantly lower latency and higher throughput, and native SCALE decoding via `parity-scale-codec`. Stable v0.1.0 follows seven beta releases with partner feedback.
+
+- Docker: `docker pull paritytech/polkadot-rest-api:v0.1.0`
+- Crate: [`polkadot-rest-api@0.1.0`](https://crates.io/crates/polkadot-rest-api)
+- GitHub: https://github.com/paritytech/polkadot-rest-api
+- Documentation: https://paritytech.github.io/polkadot-rest-api/
+- Migration guide: [MIGRATION.md](https://github.com/paritytech/polkadot-rest-api/blob/main/docs/guides/MIGRATION.md)
+- Issues/feedback: https://github.com/paritytech/polkadot-rest-api/issues
+
 ## [20.14.0](https://github.com/paritytech/substrate-api-sidecar/compare/v20.13.3..v20.14.0) (2026-02-01)
 
 ### Feat

Dockerfile.README.md

@@ -1,5 +1,20 @@
 ## substrate-api-sidecar Docker Image
 
+## ⚠️ Deprecation Notice
+
+**`substrate-api-sidecar` is deprecated in favor of [`polkadot-rest-api`](https://github.com/paritytech/polkadot-rest-api).**
+
+`polkadot-rest-api` is a ground-up Rust rewrite built on [`subxt`](https://github.com/paritytech/subxt), with 1:1 API compatibility (endpoints are served under `/v1/`, e.g. `/v1/blocks/head`), stable memory under sustained load, significantly lower latency and higher throughput, and native SCALE decoding via `parity-scale-codec`.
+
+**Migrate today:**
+- Docker: `docker pull paritytech/polkadot-rest-api:v0.1.0`
+- Crate: [`polkadot-rest-api@0.1.0`](https://crates.io/crates/polkadot-rest-api)
+- Migration guide: [MIGRATION.md](https://github.com/paritytech/polkadot-rest-api/blob/main/docs/guides/MIGRATION.md)
+- Documentation: https://paritytech.github.io/polkadot-rest-api/
+- Questions/issues: https://github.com/paritytech/polkadot-rest-api/issues
+
+---
+
 With each release, the maintainers publish a docker image to dockerhub at [parity/substrate-api-sidecar](https://hub.docker.com/r/parity/substrate-api-sidecar/tags?page=1&ordering=last_updated)
 
 ### Pull the latest release

README.md

@@ -21,6 +21,19 @@
 
 <br /><br />
 
+## ⚠️ Deprecation Notice
+
+**`substrate-api-sidecar` is deprecated in favor of [`polkadot-rest-api`](https://github.com/paritytech/polkadot-rest-api).**
+
+`polkadot-rest-api` is a ground-up Rust rewrite built on [`subxt`](https://github.com/paritytech/subxt), with 1:1 API compatibility (endpoints are served under /v1/, e.g. /v1/blocks/head), stable memory under sustained load, significantly lower latency and higher throughput, and native SCALE decoding via `parity-scale-codec`.
+
+**Migrate today:**
+- Docker: `docker pull paritytech/polkadot-rest-api:v0.1.0`
+- Crate: [`polkadot-rest-api@0.1.0`](https://crates.io/crates/polkadot-rest-api)
+- Migration guide: [MIGRATION.md](https://github.com/paritytech/polkadot-rest-api/blob/main/docs/guides/MIGRATION.md)
+- Documentation: https://paritytech.github.io/polkadot-rest-api/
+- Questions/issues: https://github.com/paritytech/polkadot-rest-api/issues
+
 ## NOTICE
 
 For the Asset hub migration please refer to the guide in [guides/ASSET_HUB_MIGRATION.md](guides/ASSET_HUB_MIGRATION.md)

docs-v2/dist/bundle.js

@@ -20,6 +20,16 @@
     <!-- Styles will be injected by webpack -->
 </head>
 <body>
+    <!-- Deprecation banner (site-wide, always visible) -->
+    <div class="deprecation-banner" role="alert" style="background: #b45309; color: #fff; padding: 12px 24px; font-size: 14px; line-height: 1.5; border-bottom: 2px solid #92400e; text-align: center; font-family: 'Inter', system-ui, sans-serif; position: relative; z-index: 10000;">
+        <strong>⚠️ Deprecation Notice:</strong>
+        <code style="background: rgba(0,0,0,0.25); padding: 1px 6px; border-radius: 3px;">substrate-api-sidecar</code>
+        is deprecated in favor of
+        <a href="https://github.com/paritytech/polkadot-rest-api" target="_blank" rel="noopener" style="color: #fff; text-decoration: underline; font-weight: 600;">polkadot-rest-api</a>
+        — a Rust rewrite with 1:1 API compatibility.
+        <a href="https://github.com/paritytech/polkadot-rest-api/blob/main/docs/guides/MIGRATION.md" target="_blank" rel="noopener" style="color: #fff; text-decoration: underline; font-weight: 600;">Migration guide →</a>
+    </div>
+
     <!-- Loading screen -->
     <div id="loading-screen" class="loading-screen">
         <div class="loading-spinner">

docs-v2/dist/index.html

@@ -1,8 +1,21 @@
 openapi: 3.0.0
 info:
   title: Substrate API Sidecar
-  description: Substrate API Sidecar is a REST service that makes it easy to
-    interact with blockchain nodes built using Substrate's FRAME framework.
+  description: |
+    > ⚠️ **Deprecation Notice** — `substrate-api-sidecar` is deprecated in favor of
+    > [`polkadot-rest-api`](https://github.com/paritytech/polkadot-rest-api), a ground-up Rust rewrite
+    > built on [`subxt`](https://github.com/paritytech/subxt) with 1:1 API compatibility (endpoints
+    > served under `/v1/`, e.g. `/v1/blocks/head`), stable memory under sustained load, significantly
+    > lower latency and higher throughput, and native SCALE decoding via `parity-scale-codec`.
+    >
+    > **Migrate today:** Docker `paritytech/polkadot-rest-api:v0.1.0` ·
+    > [crate](https://crates.io/crates/polkadot-rest-api) ·
+    > [migration guide](https://github.com/paritytech/polkadot-rest-api/blob/main/docs/guides/MIGRATION.md) ·
+    > [docs](https://paritytech.github.io/polkadot-rest-api/) ·
+    > [issues](https://github.com/paritytech/polkadot-rest-api/issues)
+
+    Substrate API Sidecar is a REST service that makes it easy to interact with blockchain nodes
+    built using Substrate's FRAME framework.
   contact:
     url: https://github.com/paritytech/substrate-api-sidecar
   license: