# ddz.dev

> Legacy modernization and software consulting by Dušan Dželebdžić. I connect decades-old systems to modern infrastructure, migrate what's ready, and keep the rest running. I also fix broken systems and build custom software for industrial settings. 30 years of experience. For larger projects I bring in a network of trusted specialists (full-stack architects, pentesters, frontend developers) while staying the single point of contact and responsibility.

## Services

- [Legacy Modernization](https://ddz.dev/): the strongest offer. Keeping critical old systems alive and connected while the business moves forward: integrations with modern infrastructure, data extraction and migration off legacy platforms, and staged retirement. Covers everything from OpenVMS to aging PHP monoliths.
- [Custom Development](https://ddz.dev/): custom web apps, mobile apps, and integrations, mostly for industrial settings. Design, build, and ship, backed by 30 years of experience.
- [Software Consulting](https://ddz.dev/): emergency fixes, system audits, and ongoing support for production systems, infrastructure, and integrations between systems that don't talk to each other.
- [OpenVMS Consulting](https://ddz.dev/openvms/): the deepest legacy end covered. Maintenance, debugging, and modernization of OpenVMS systems. COBOL, RMS, Rdb, DCL, and integration with modern infrastructure. Remote-first, worldwide.

## About

- [Homepage](https://ddz.dev/)
- [About](https://ddz.dev/about/)

## Blog

- [Vercel Web Analytics served its script from a path with no leading slash](https://ddz.dev/blog/vercel-web-analytics-script-path-404/)

- [PHP's sprintf pads by bytes, so one † moved my table columns](https://ddz.dev/blog/php-sprintf-pads-by-bytes/)

- [aws_instance must be replaced, because Amazon published a new AMI](https://ddz.dev/blog/terraform-most-recent-ami-replaces-ec2-instance/)

- ["zsh: bad CPU type in executable" after upgrading to macOS 27](https://ddz.dev/blog/bad-cpu-type-in-executable-macos-27/)

- [PostHog cookieless mode said 200 Ok and dropped every pageview](https://ddz.dev/blog/posthog-cookieless-200-ok-events-dropped/)

- [Moving a Route 53 hosted zone between AWS accounts](https://ddz.dev/blog/route53-hosted-zone-between-accounts/)

- [Tailscale SSH: connection refused, permission denied, and which server actually answered](https://ddz.dev/blog/tailscale-ssh-connection-refused-permission-denied/)

- [280 vulnerabilities, one unused package](https://ddz.dev/blog/280-vulnerabilities-one-unused-package/)

- [mount.cifs said the credentials were formatted incorrectly. It was right.](https://ddz.dev/blog/mount-cifs-credential-formatted-incorrectly/)

- [LocalStack exited with code 55 after a routine image update](https://ddz.dev/blog/localstack-license-activation-failed/)

- [The filename that works in bash and breaks in zsh](https://ddz.dev/blog/tilde-in-filename/)

- [Dart Sass quietly reordered my CSS](https://ddz.dev/blog/dart-sass-mixed-declarations-reordered-css/)

- ["Cannot connect to MySQL using SSL" is a hostname problem](https://ddz.dev/blog/cannot-connect-to-mysql-using-ssl/)

- [Never let the LLM write the subject line](https://ddz.dev/blog/llm-subject-line-gmail-threading/)

- [Restate's default node name is your container hostname](https://ddz.dev/blog/restate-node-name-container-hostname/)

- [Symfony 8 ignores your #[Groups] attribute](https://ddz.dev/blog/symfony-8-groups-attribute-silently-ignored/)

- [The database was fine. The cloud around it wasn't.](https://ddz.dev/blog/azure-managed-postgres-connection/)

- [Tailscale SSH fails with "tailnet policy does not permit access"](https://ddz.dev/blog/tailscale-ssh-tailnet-policy/)

- [Modernization usually means rewriting everything wrong](https://ddz.dev/blog/modernization-usually-means-rewriting-wrong/)

- [NAT Gateway is eating your AWS bill](https://ddz.dev/blog/aws-nat-gateway-bill/)

- [WordPress fleets on AWS are rotting from the database up](https://ddz.dev/blog/wordpress-fleets-on-aws/)

- [The one setting that stops Microsoft Authenticator spam](https://ddz.dev/blog/microsoft-authenticator-spam-notifications/)

- [Your server is running two PHP versions (and one of them is lying)](https://ddz.dev/blog/php-cli-vs-apache-mismatch/)

- [Stop all running containers in Docker](https://ddz.dev/blog/docker-stop-all-containers/)

- [Why Docker?](https://ddz.dev/blog/why-docker/)


## Projects

- [Why I built WebKeeper after a decade of running an agency](https://ddz.dev/blog/webkeeper/)

- [Biro](https://ddz.dev/blog/biro/)

- [iOS Utility](https://ddz.dev/blog/ios-utility/)

- [Mozgalice](https://ddz.dev/blog/mozgalice/)

- [Tempmarks](https://ddz.dev/blog/tempmarks/)


## Contact

- Email: hello@ddz.dev
- Phone: +1 929 888 7421