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Software for systems where mistakes are expensive.

I build the systems regulated companies can't afford to get wrong: identity, claims and filings. I also build AI agents that complete that paperwork, and ask a person when something doesn't add up.

Healthcare claims
Intake and EDI reconciliation for US health plans
Banking identity
Customer identity and signing for a European banking group
AI agents
A filing agent with human review, in production
Discuss your systemSee the work

Selected work

All work (4)

Visa applicationsIn production

An agent that completes visa filings

An AI agent fills visa applications from the applicant's documents, and a browser extension carries them into official portals that have no API.

  • Schengen, US, UK, Turkey, UAE and more
  • Visa services platform (NDA)
Read the case studyJava & Spring Boot, AWS Bedrock, RabbitMQ, Stripe
Visa agent: Schengen tourist visa
  • My wife is travelling with me. She has her own passport.
Passport number
···
Travel dates
···
Co-applicant
···
Bank statement
···
EUSchengen visa0 of 4 fields
Browser extension: fills the official visa portalWaiting

Healthcare claimsIn production

Claims intake and EDI reconciliation for US health plans

Every claim file traced from SFTP drop to payer acknowledgement, across several US health plans with their own rules.

  • Multiple US health plans
  • 837 claims reconciled against TA1, 999 and 277
Read the case studyJava & Spring Boot, AWS S3 & SQS, PostgreSQL, X12 EDI
Claims intake: one batch, end to end
  1. Batch received from SFTPMoved to S3 with a manifest; duplicate drops are ignored
  2. Pages prepared and extractedImages cleaned before recognition runs
  3. Plan rules appliedNormalization and validation for this health plan's module
  4. 837 sent, TA1 and 999 acceptedEnvelope and syntax acknowledgements matched
  5. 277 not receivedClaim stays open for follow-up until it arrives
837Batch 2291, claims submitted0 of 5

Banking identityIn production

Customer identity and transaction signing for a retail bank

One customer identity kept consistent across four banking systems, with half-finished changes undone automatically.

  • Retail bank, European banking group
  • Four systems kept consistent per change
Read the case studyJava & Spring Boot, Keycloak, OAuth 2.0 / OIDC, HID authentication
Customer identity: creation that fails halfway
  1. Request validatedRequired fields and uniqueness checked before any system is touched
  2. Authenticator user createdCustomer registered on the device platform
  3. Login account failedIdentity provider rejected the account
  4. Authenticator user removedCompensating step undoes the earlier one
  5. Operation loggedRequest and outcome written to the identity audit log
IDNew customer, rolled back cleanly0 of 5

Services

All services

Your paperwork is still done by hand.

AI agents for document-heavy workflows

How it works

Your backend has become the bottleneck.

Backend architecture & systems integration

How it works

You need a first version you won't have to rewrite.

End-to-end product development

How it works

Who you'd work with

Portrait of Nikola Peković

I'm Nikola Peković, a senior software engineer. I build the software regulated companies rely on every day, and I work side by side with the people who run it, from the first conversation to the day it runs without me.

7+ years building production systems, and 10+ systems shipped to production.

Full background

Working together

Start with a small, paid first step. You own everything from the first commit.

Terms and FAQ

  1. Discovery

    1 to 2 weeks, fixed price

  2. Build

    Fixed scope or weekly rate

  3. Retainer or handover

    Monthly, cancel anytime

If mistakes in your system are expensive, let's talk.

Tell me what's at stake. You'll hear back within one business day, and the first call is 30 minutes, with no obligation.

Discuss your system

or email contact@nikolapekovic.com