Running customer code safely inside InDoc EDGE

InDoc EDGE manages documents and business processes for enterprises in regulated sectors, from capture and approval to electronic signing and long-term archiving. Its customers include OTP banka, Luka Koper and GLS.

Mikrocop’s roadmap held more work than its development team could deliver within the release schedule. Complete modules were planned with no one free to build them, and a new Scripting Sandbox needed expertise the in-house team did not have.

The sandbox was the hardest part. Customers write C# scripts in the process editor to add their own calculations and rules, so the platform has to run code it does not control. In the previous environment, a script could stop a sandbox instance or reach the machine it ran on.

The sandbox was a fixed-price project. We owned its specification, architecture, development, testing and documentation.

It is a separate .NET service that InDoc EDGE calls over gRPC. Each script runs in its own isolated Linux process, with limited computing resources and no access to the host machine. More instances can be added as load grows, and they can be shared between InDoc EDGE deployments, with load balancing on the calling side. Redis caches compiled scripts, and a fallback to the legacy sandbox covered the transition.

We also delivered three modules independently, refining tickets with Mikrocop’s product owners and estimating with its technical team. For Document Signing, we rewrote Mikrocop’s internal library for creating and verifying digital signatures on current platform APIs. The External API work moved more configuration into InDoc EDGE’s own settings and added JWT authentication, with compatibility checks against existing client integrations. Bookmarks added organisation-wide bookmarks, controlled by administrators with full access control, alongside personal ones.

With the modules delivered, the wider roadmap still needed people. Our engineers joined Mikrocop’s core team and worked within its process, from specification to testing.

We extended the BPMN workflow engine, which models each business process, and rewrote the access control system. We traced and fixed hard defects, including multi-tenant context leaks and race conditions in distributed concurrent processing, and helped move the frontend from Durandal to React.

On the frontend, we designed in-app back navigation that behaves like a browser’s, with fallbacks that replaced hardcoded routes. We added form components for complex input and carried out the major package upgrades: React Query to v5, the deprecated MUI packages and react-i18next.

The releases we worked on shipped 30% more feature tickets than the releases before we joined, a record for InDoc EDGE.

Document signing and verification became 65% faster on a substantially simpler codebase. The new sandbox runs at twice the throughput of the previous environment, and scripts can no longer stop an instance or reach the machine it runs on. After the External API changes, some client-requested integrations need up to 90% less work, and one class of custom integration no longer has to be maintained.