API-First on 1C-Bitrix: REST, OAuth, and Caching

A client approached us with a challenge: an e-commerce site on Bitrix, a React frontend, an iOS/Android mobile app, and 1C integration. Classic components wouldn't work—they needed JSON. We developed an API-first architecture: Bitrix became the backend serving data through REST APIs. The frontend team works against a contract, unaware of info blocks. The result—an average maintenance cost savings of 35% thanks to a unified API contract, and time-to-market for new features on mobile platforms reduced by 2–3x. We have specialized in such solutions for over 10 years. We have 50+ projects where Bitrix acts as an API server. Average API response time is 80 ms under peak loads up to 5000 RPS. Contact us for a free project assessment.

API-First vs Classic Bitrix: What's the Difference?

API-first radically differs from classic development. The component bitrix:catalog.section renders HTML on the server. The API approach outputs JSON—the frontend controls rendering. This gives:

• 2–3x faster mobile app development compared to the classic approach.
• A single integration point for all clients: web, iOS, Android, B2B partners.
• Full frontend control: React/Vue SPA with SSR, Swift, Kotlin.

When Is API-First Justified?

API-first on Bitrix makes sense if:

• There are multiple frontend clients sharing the same business logic.
• You need full control over the frontend (React/Vue SPA with SSR).
• The mobile app is a full product component, not an afterthought.
• You anticipate integration with many external systems through a single entry point.

If it's just a website without a mobile app, API-first is overkill.

How to Ensure API Performance?

Without caching, an API server becomes a load generator: every hit from a mobile app means N database queries. Strategy:

• HTTP cache (Cache-Control: max-age=300, ETag): for public resources (catalog, articles). CDN caches on its side.
• Redis/Memcached: complex aggregated responses (product page = iblock data + catalog prices + stock + reviews). TTL 5–15 minutes, tag-based invalidation on data change.
• Bitrix tagged cache: \Bitrix\Main\Data\TaggedCache—invalidate cache for a specific product when it is updated via 1C exchange.

Key Technical Solutions

Architecture

Clients
 ├── React SPA (web)
 ├── React Native / Swift / Kotlin (mobile)
 └── External systems (B2B partners, ERP)
         ↓ HTTPS/JSON
   API layer (custom REST endpoints on Bitrix)
         ↓
   Business logic (modules catalog, sale, iblock, custom)
         ↓
   Database (MySQL/PostgreSQL)

Implementing REST Endpoints

In Bitrix24 and 1C-Bitrix (on-premise), there is a mechanism to register custom REST methods via the event OnRestServiceBuildDescription. According to 1C-Bitrix documentation, this is the standard path.

// /local/modules/vendor.api/lib/resthandler.php
class RestHandler
{
    public static function onRestServiceBuildDescription(): array
    {
        return [
            'vendor' => [
                'catalog.product.list' => [
                    'callback' => [self::class, 'getCatalogProducts'],
                    'options' => ['private' => false],
                ],
                'catalog.product.get' => [
                    'callback' => [self::class, 'getCatalogProduct'],
                    'options' => ['private' => false],
                ],
                'sale.order.create' => [
                    'callback' => [self::class, 'createOrder'],
                    'options' => ['private' => false],
                ],
            ],
        ];
    }
}

An alternative is a controller component at a separate URL (/api/v1/) that accepts requests without using the Bitrix REST mechanism.

API Client Authorization

Comparison of methods:

OAuth 2.0 is the standard path for public API. The client gets an access_token via Authorization Code or Client Credentials flow. Tokens are stored in b_oauth_access_token. Bitrix supports OAuth out of the box via the oauth module.

JWT for server-to-server and mobile clients. Server signs JWT with its own key, client passes in Authorization: Bearer header. Verify on each request—no DB access (stateless).

API Key for B2B partners with fixed IP.

How to Version API Without Pain?

Scheme: /api/v1/catalog/products, /api/v2/catalog/products. v1 and v2 live in parallel. v1 is declared deprecated with a retirement date communicated to clients via Deprecation and Sunset headers.

OpenAPI Specification

All endpoints are documented in OpenAPI 3.0 format. The frontend team generates a typed client (TypeScript SDK, Swift/Kotlin clients), QA engineers automate testing against the specification.

Error Handling

Unified error format for all endpoints:

{
  "error": {
    "code": "PRODUCT_NOT_FOUND",
    "message": "Product with ID 12345 not found",
    "details": {}
  }
}

HTTP codes are used semantically: 404—not found, 422—validation error, 429—rate limit exceeded, 503—service temporarily unavailable.

Testing

An API without tests is an API without trust. We cover:

• Unit tests on handler business logic.
• Integration tests on endpoints (PHPUnit + real test DB).
• Contract tests—verify response matches OpenAPI schema (Dredd, Schemathesis).

Process of Work

What's Included

• API design: resources, endpoints, OpenAPI specification.
• Development of REST endpoints with authorization and caching.
• Swagger UI documentation with request examples.
• Integration testing.
• Handover of source code, deployment instructions, accesses.
• Training your team on API usage.
• Support during launch phase.

How to Implement a REST Endpoint in 5 Steps

1. Define a resource and endpoints (e.g., /api/v1/catalog/products).
2. Create a handler class with methods list, get, create, update, delete.
3. Register the endpoint via the event OnRestServiceBuildDescription.
4. Add authorization (OAuth, JWT, API Key).
5. Test via Swagger UI and contract tests.

Development Phases

API-first on Bitrix is an additional abstraction layer that requires team discipline. But frontend developers work with a clean JSON contract and know nothing about components and info blocks. We guarantee quality: every project undergoes code review and load testing. Order an architecture consultation and get an assessment of your API-first solution.

1C-Bitrix Module Development and Setup

The main trap of Bitrix is init.php. You add an OnBeforeIBlockElementUpdate handler there, then another one — a year later the file is 2000 lines, and on every hit all that code executes. We move business logic into full-fledged modules with D7 ORM, custom tables, and administrative interface. The module can be disabled, transferred to another project, covered with tests — none of that is possible with init.php. Our team has 10+ years of Bitrix experience, certified specialists, and a 6-month code guarantee. Request a consultation — we'll explain how to migrate legacy code to a modular architecture.

Why is init.php the worst place for business logic?

Init.php does not support class autoloading, lacks an isolated namespace, cannot be unit tested, and cannot be disabled without editing the file itself. Every handler written there runs on every request, even if not needed. In a module, you register handlers through EventManager, and they only execute when the event occurs. Performance difference: up to 3x with 10+ handlers.

Standard Modules: Typical Problems and Solutions

Information blocks. IBlock architecture is the first thing we review on any project. A classic mistake: one catalog infoblock with 80 properties, 30 of which are multiple. The b_iblock_element_property table swells to millions of rows, and CIBlockElement::GetList with filtering on three properties does a full scan. We move reference data to Highload-blocks, eliminate multiple properties where possible, and design the structure for 5x growth.

e-Store (sale). Cart business rules are a separate story. We set discount priorities to prevent two campaigns from giving 60% instead of 30%, connect payment handlers, and write custom validation via OnSaleOrderBeforeSaved.

Search. The built-in search module with morphology works up to 10–15 thousand elements. Beyond that — Elasticsearch. We configure it via the Bitrix search module API, indexing through CSearchFullText or custom indexers.

Highload-blocks for dictionaries, logs, user data — instead of bloated IBlocks. Direct queries via Bitrix\Highloadblock\HighloadBlockTable, custom tables instead of the EAV structure of standard infoblocks. A million records — no degradation.

Mail events. Configuration is not just templates in b_event_message. The key is SPF, DKIM, DMARC on the DNS, otherwise transactional emails go to spam. We check deliverability and set up bounce handling.

How to Design Infoblocks for Performance?

We use Highload-blocks for reference data (colors, sizes, manufacturers) that are not involved in complex queries. For SKUs — a separate infoblock with linking via IBLOCK_ELEMENT_PROPERTY. Enable INDEX_PROPERTY for frequently filtered properties. Tagged caching: when an element changes, only the related cache is cleared. Highload-blocks process up to 10x faster than infoblocks with multiple properties on volumes of 100,000 records.

Custom Module Development

Each module follows the structure /local/modules/vendor.modulename/:

• install/index.php — setup class, create tables via $DB->RunSQLBatch()
• lib/ — D7 ORM classes, extending Bitrix\Main\ORM\Data\DataManager
• admin/ — administrative pages using CAdminList, CAdminForm
• include.php — autoloading, event handler registration via EventManager::getInstance()->registerEventHandler()
• REST API endpoints via \Bitrix\Rest\RestManager

The module registers in the system, appears in the "Installed Solutions" list, and has its own settings at /bitrix/admin/settings.php?mid=vendor.modulename. It can be enabled, disabled, and updated through UpdateSystem or custom migration mechanics.

Examples of implemented tasks:

• Campaign management — visual condition builder via CAdminCalendar, timers via agents (CAgent::AddAgent), analytics linked to the sale module
• Cost calculator — React widget on the frontend, REST API in the module, formulas stored in a Highload-block
• Booking system — real-time calendar, locking via $DB->StartTransaction() / $DB->Commit() on concurrent requests, integration with channel manager via webhook

Components and Composite Cache

Component customization via result_modifier.php and component_epilog.php, not by editing template.php of the standard template. This way core updates are painless.

Composite cache ("Composite Site" technology) — the server sends ready HTML, bypassing PHP routing. Dynamic areas (cart, authorization) are loaded via CBitrixComponent::setFrameMode(true) and AJAX. TTFB drops to 30–50 ms. But there are caveats: not all components are compatible, $APPLICATION->ShowPanel() breaks composite, and careful markup of <div id="bx-composite-..."> is required.

What to Check Before Installing a Marketplace Module?

Before installing a module from the marketplace, an audit is mandatory. We check: SQL queries without prepared statements (hello SQL injection), direct use of $_REQUEST without filtering, use of outdated kernel API instead of D7, conflicts with the composite cache module. A module with no updates for over a year and a few dozen installations is likely a problem on the next PHP update. A typical case: a module calls CIBlockElement::GetList with no cache reset — the site crashes with 5000 elements.

Migration to D7

When upgrading PHP or switching to a new edition — refactor outdated calls:

• CIBlockElement::GetList() → Bitrix\Iblock\Elements\ElementTable::getList()
• CSaleOrder::GetList() → Bitrix\Sale\Order::getList()
• CModule::IncludeModule() → Bitrix\Main\Loader::includeModule() Testing on staging, rollback via git on issues.

According to official 1C-Bitrix documentation, D7 ORM is the recommended tool for working with data, providing type safety and automatic query generation.

Comparison: Init.php vs Module

Module Development Scope and Cost

What is included in module development?

• Technical specification and architectural plan
• Code following PSR-4 and Bitrix code style
• Unit tests (PHPUnit) for business logic
• Integration tests for events and REST API
• Installation, configuration, and API documentation
• Repository and documentation access
• Administrator training for module usage
• 6-month warranty support

Estimated timelines and complexity:

Cost is calculated individually — contact us for a project estimate.

Module Testing

Unit tests via PHPUnit cover business logic: discount calculation, validation, document generation. Mocks for Bitrix\Main\Application::getConnection() allow tests to be DB-independent. Integration tests verify event handlers on a real database — OnAfterIBlockElementAdd, OnSaleOrderSaved, etc. REST API endpoints are tested via curl or PHPUnit HTTP client. Critical for modules working with b_sale_order, b_catalog_price — where errors cost money.

Compatibility is checked on PHP 7.4, 8.0, 8.1, 8.2 and editions: Standard, Small Business, Business. We check conflicts with popular marketplace modules — they often intercept the same events. Load testing: measurements on 10K, 100K, 1M records, profiling via Xdebug for memory leaks and N+1 queries.

Practical Examples

Campaign module for an electronics chain. The built-in sale module discounts did not cover scenarios like "2+1", a gift with purchase over a certain amount, or combined conditions. We built a visual builder: marketers create rules via drag-and-drop without development tickets. Campaign calendar, auto-deactivation via agents, analytics linked to b_sale_order — conversion, average check, usage count. Time to launch a new campaign dropped from two days to half an hour.

Calculator for builders. Parameters (area, materials, number of floors) → formula → preliminary estimate → lead to CRM via CRest::call('crm.lead.add'). Regional coefficients and seasonal markups from a Highload-block, material prices from 1C exchange. The number of target leads increased by a third: clients see a breakdown before calling a manager.

Booking for a hotel chain. Real-time availability via AJAX requests to a custom table vendor_booking_slots, seasonal tariff calculation, synchronization with Booking.com via channel manager API. Room locking on concurrent booking via SELECT ... FOR UPDATE in transactions. Timezones handled via \DateTimeZone — a guest from Vladivostok and a manager from Moscow see the same picture.

We will evaluate your project within one day. Write to us — we'll tell you what is included in turnkey development. Contact us for a consultation on your project. Order a custom module development — get a ready solution with documentation and support.