> For the complete documentation index, see [llms.txt](https://api-docs.flagstoneim.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://api-docs.flagstoneim.com/readme.md).
# Flagstone API Documents
We're the UK leader in savings API integration.
We connect pension providers, wealth managers, and financial institutions to 60+ banks through one integration.
Our APIs have powered our multi-billion pounds savings platform since 2019.
Partners use them every day to open accounts, receive interest, and report client balances in a regulated UK context.
| | |
| ------------------------------------------------------------ | ----------------------------------------------- |
| **In production since** | 2019 |
| **Instructions processed annually** | 100 million+ |
| **Capital transferred to date** | £100 billion+ |
| **Partner bank network** | 60+ banking institutions |
| **Sustained throughput** | Up to 50 requests/second |
| **Processing window** | 24-hour instruction cycle |
| **Regulatory status** | FCA authorised and regulated |
| **Client coverage** | Individual, Company |
| **FSCS (Financial Services Compensation Scheme) protection** | Per-product, per-institution visibility via API |
Whether you run a large pension scheme or a SIPP (Self-Invested Personal Pension) proposition, the pattern is simple.
You integrate once with a mature, version-stable API suite and scale with confidence.
***
## 🔗 Core Integration Flow
1. **Register your client** - Individual or company, via the Client API
2. **Browse available products** - Fixed term, instant access, and notice accounts via the Product Catalog API
3. **Submit instructions** - Deposits, withdrawals, and other operations via the Instruction Request API
4. **Track positions** - View deposit accounts, interest, and pending payments via the Portfolios API
***
## 📚 API Suite
| API | What it does | Version |
| -------------------------------------------------------- | ---------------------------------------------------- | ------------ |
| [Client API](/apis/clients.md) | Onboard and manage individual & company clients | `2020-08-01` |
| [Product Catalog API](/apis/products.md) | Browse savings products, rates, and terms | `2022-07-01` |
| [Instruction Request API](/apis/instruction-requests.md) | Submit deposits, withdrawals, and other instructions | `2021-11-01` |
| [Portfolios API](/apis/portfolios.md) | View client portfolios and deposit account positions | `2020-04-01` |
| [Instruction Batches API](/apis/instruction-batches.md) | View and manage daily instruction settlement batches | - |
Each API has a dedicated guide with business context, endpoint reference, and request/response examples. Full OpenAPI 3.0 specifications are available for each:
* [Client API Reference](/api-reference/client-api-ref.md)
* [Products API Reference](/api-reference/products-api-ref.md)
* [Instruction Request API Reference](/api-reference/instruction-request-api-ref.md)
* [Portfolios API Reference](/api-reference/financial-partners-api-ref.md)
* [Instruction Batches API Reference](/api-reference/instruction-batches-api-ref.md)
***
## 🏗️ Platform Architecture
| Capability | Detail |
| ----------------------- | ----------------------------------------------- |
| **Authentication** | API key via `cdpapi-Subscription-Key` header |
| **Environments** | Sandbox and Production |
| **Specification** | OpenAPI 3.0.1 for all APIs |
| **Client types** | Individual and Company |
| **Currencies** | GBP, EUR, USD |
| **Product types** | Fixed Term, Instant Access, Notice |
| **FSCS protection** | Visibility per product and institution |
| **Concurrency control** | Optimistic versioning on clients and portfolios |
| **Idempotency** | Built-in |
***
## 🚀 Quick Start
1. [Get your API credentials](/getting-started.md) - sandbox and production keys
2. [Understand the data model](/core-concepts.md) - how clients, products, instructions, and portfolios relate
3. [Create your first client](/apis/clients.md) - start with the Client API
4. [Submit your first deposit](/apis/instruction-requests.md) - place an instruction against a product
---
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