A secure, serverless Next.js and Postgres database deployment designed to bypass the licensing tax of SAP S/4HANA — with 100% code ownership at handover.
Lock-in profile: Extreme (ABAP ecosystem, complex upgrade lockouts)
In short: ERPStack provides a custom, license-free alternative to SAP S/4HANA. You get 100% data and IP ownership, zero seat-based fees, and a dedicated cloud deployment delivered in weeks.
Vivek Mishra — Founder & Lead Architect, ERPStack
Most S/4HANA replacement projects start with a date, not a feature. SAP gives mainstream maintenance for Business Suite 7 until the end of 2027, and moving to S/4HANA is a programme in its own right. If you are rebuilding anyway, a headless ERP on Next.js, Node.js and PostgreSQL is a live option — extracted module by module behind an API gateway, with no named-user licence and the source in your own repository. A first domain usually leaves S/4HANA inside 4 weeks; a full programme runs 12-24 weeks.
SAP announced a maintenance commitment for S/4HANA until the end of 2040. That is a longer and more specific runway than almost any vendor offers, and for a plant running the same process for 20 years it is worth paying for. S/4HANA's process depth in manufacturing, logistics and statutory reporting is genuine, and a custom build reproduces only the parts you actually use.
Domains extracted one at a time into Node.js services behind a REST API gateway, with PostgreSQL and Drizzle ORM replacing SAP HANA tables and Apache Kafka carrying change events to a React and TypeScript front end. RBAC, SSO and an immutable audit trail on every posting. Terraform and Docker for infrastructure, GitHub Actions for CI/CD deployment pipelines, Sentry and OpenTelemetry Observability for monitoring. Deployed to AWS or Microsoft Azure under your contract, not SAP's.
Deploy an API gateway to proxy requests between legacy SAP S/4HANA and new Node.js microservices.
Extract domains (e.g., HR, Inventory) from SAP S/4HANA one by one — phase 2 of the four-phase implementation timeline.
Real-time replication from SAP HANA to PostgreSQL via Debezium and Apache Kafka.
Turning off the legacy SAP modules permanently after 30 days of clean parallel-run validation.
7 of 7 capabilities shown
| Capability | Custom ERPStack build | SAP S/4HANA |
|---|---|---|
| Deployment SpeedOperations | Days/Weeks (Vercel Edge) | Months/Years (On-prem or SAP Cloud) |
| Developer EcosystemExtensibility | TypeScript / React / Node.js | ABAP / Proprietary SAP tools |
| Real-time AnalyticsData & Ownership | Embedded ClickHouse Analytics Database alongside PostgreSQL | Requires a separate SAP BW/4HANA instance |
| Source AvailabilityPlatform | Full application source in your repository, on public open-source runtimes (React, PostgreSQL, Node.js) | ABAP application source is inspectable by licensed customers, but the runtime and platform are proprietary and cannot be self-hosted independently of SAP licensing |
| Manufacturing & Plant Maintenance (MRP/CMMS)Operations | MRP runs and CMMS maintenance scheduling engineered to your shop-floor requirements, with job costing for construction and project-based operations | PP and PM modules each licensed and configured separately |
| Business User ExperienceOperations | Role-specific React dashboards sized for the mid-size firm; user management and free read-only seats included | SAP GUI/Fiori access licensed per named user |
| Software Selection & ReviewsPlatform | One 2-week expert requirements audit replaces months of comparing vendors — the benefits and trade-offs land in a management-ready decision document | RFP cycles across analyst reviews, demo scripts, and integrator options |
On SAP S/4HANA, stacked on the $100,000 - $1,000,000+ / year base license.
SAP requires certified integrators. Minor UI changes can cost $50k+ in consulting hours.
On SAP S/4HANA, stacked on the $100,000 - $1,000,000+ / year base license.
In-memory databases are incredibly expensive for cold/archival data. A custom build keeps hot data in PostgreSQL and archives cold records to object storage at a fraction of the per-GB cost — typically over 10x cheaper.
On SAP S/4HANA, stacked on the $100,000 - $1,000,000+ / year base license.
SAP provides mainstream maintenance for core SAP Business Suite 7 applications until the end of 2027, with optional extended maintenance to the end of 2030. Moving to S/4HANA is itself a re-implementation for most estates — so the budget is being spent either way, and the only open question is what it buys.
On SAP S/4HANA, stacked on the $100,000 - $1,000,000+ / year base license.
Choosing between S/4HANA editions consumes months of vendor research, user reviews, and integrator options before any build starts. Hire one team instead: a fixed 2-week requirements audit produces a management-ready decision document.
Drag the team-size slider to model SaaS licensing spend against a fixed-cost custom build — implementation, hosting, and 3-year TCO update in real time.
Staying on per-seat licensing costs you $4,365 every month at 50 seats — spend that never converts into owned IP.
Yes, and at this size it is the only sane approach. A REST API gateway sits in front of SAP S/4HANA and proxies requests while domains move out one at a time behind it, using the strangler fig migration pattern. Data replicates continuously from SAP HANA into PostgreSQL, with Drizzle ORM over the new schema, so both systems stay consistent through the overlap. Most teams have a first domain running outside S/4HANA within about 4 weeks, and nobody experiences a big-bang cutover because there is not one.
It has to be engineered for that, not assumed. The architectures we design for SAP S/4HANA replacement use serverless edge routing on Node.js, a replicated PostgreSQL primary and an immutable audit trail on every financial write, targeting 99.9% availability with multi-region failover on AWS. The honest caveat: SAP has thousands of engineers on this problem and you will have one team. That is exactly why we replace the modules you depend on and leave the rest in place.
SAP provides mainstream maintenance for core SAP Business Suite 7 applications until the end of 2027, with optional extended maintenance to the end of 2030. Moving to S/4HANA is itself a full re-implementation for most estates. So the real question is not "S/4HANA or custom" but "which re-implementation do we want to fund", and that is a far more open decision than a vendor roadmap makes it look.
No. SAP itself sells extended maintenance from the start of 2028 to the close of 2030 at a premium of two percentage points, and moves customers who decline it to customer-specific maintenance at unchanged fees. Third-party maintenance is a real option too: Rimini Street publishes support for SAP ERP ECC 6.0 through 2040 and beyond and advertises up to 50% off annual SAP support fees, and Spinnaker Support advertises an average 62% reduction. Those are vendor marketing figures, not audited ones. Saying this cuts against our own urgency, which is exactly why it belongs here.
Companies whose statutory reporting, plant maintenance or global trade requirements are already met by standard S/4HANA modules, and who value the maintenance commitment running to 2040. If your ABAP estate is small and your processes sit close to SAP S/4HANA standard, the upgrade path is cheaper than a rebuild. Custom wins where modifications are heavy, per-user licensing bites, or a process has to bend to the software rather than the reverse.
Every figure below was read from the vendor’s own published page on 2 August 2026. Vendor terms change without notice — follow the link and check the number yourself before you decide anything on it. Whatever we could not source that way is not on this page.
SAP announced a maintenance commitment for SAP S/4HANA until the end of 2040 — an unusually long, dated guarantee that no custom ERP team can match on paper, and it belongs on the incumbent's side of the ledger.
SAP provides mainstream maintenance for core applications of SAP Business Suite 7 until the end of 2027, followed by optional extended maintenance until the end of 2030. That deadline, not a feature gap, is what puts most SAP estates into an evaluation of SAP S/4HANA against a custom ERP.
SAP's indirect access guide for installed-base customers defines Indirect Access as use of the ERP system "via a non-SAP intermediary software between the users and the SAP ERP system, such as a non-SAP front-end, a custom solution, or a third-party application". Under the pre-April-2018 model that use is licensed primarily by Users, with indirect order-to-cash and procure-to-pay licensed by Sales Orders and Purchase Orders; SAP's newer model prices the same use by document. Putting a custom interface in front of SAP S/4HANA is a licensing question before it is an engineering one — including when we are the ones building it.
SAP — Indirect Access Guide for SAP Installed Base Customers, April 2018 (read 15 August 2026)
SAP's Digital Access model counts nine system-generated document types — sales, invoice, purchase, service and maintenance, manufacturing, quality management, time management, financial and material — and states the licence calculation is based on the initial document created, with read, update and delete not counted. An integration that creates documents in SAP S/4HANA therefore carries a cost your seat count never shows, and the multiplier differs by document type.
SAP — Digital Access Adoption Program overview, May 2020 (read 15 August 2026)
SAP offers extended maintenance for SAP Business Suite 7 for three additional years, from the start of 2028 to the close of 2030, at "a premium of two percentage points on the existing maintenance basis". Customers who do not choose it by the end of 2027 are automatically transferred to the customer-specific maintenance model, which SAP describes as problem solving for known issues at unchanged fees. The deadline is a decision point, not a switch-off.
SAP News — maintenance commitment press release (re-read 15 August 2026)
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