Deploy your JavaScript app to Fly.io
Step-by-step deployment help for JavaScript apps on Fly.io. We fix JavaScript-specific deployment issues, configure Fly.io, and get your app live. From $19.
JavaScript issues we fix before deploying
Common JavaScript problems that affect Fly.io deployments.
Prototype pollution
AI-generated code merges user-supplied objects into prototypes via Object.assign or spread operators without sanitization, enabling property injection attacks.
Loose equality comparisons
Using == instead of === leads to type coercion bugs where '0' == false, null == undefined, and other non-obvious truthy/falsy comparisons cause silent logic errors.
Unhandled promise rejections
Async functions without try/catch or .catch() handlers cause unhandled rejection warnings and silent failures in production.
Global variable leaks
Missing 'const' or 'let' declarations create implicit globals that pollute the global scope and cause unpredictable behavior across modules.
Fly.io deployment issues we check for
Common Fly.io problems that break JavaScript apps in production.
Dockerfile missing or misconfigured
Fly.io requires a Dockerfile for deployment. AI tools that scaffold without one force flyctl to auto-generate a suboptimal Dockerfile that misses build steps.
Volume only available in a single region
Fly volumes are pinned to one region. Multi-region deployments try to access a volume that doesn't exist in other regions, causing crashes.
Machine restarts losing in-memory state
AI-generated apps store session data or caches in memory. Fly machines can restart or migrate, wiping all in-memory state without warning.
Internal DNS resolution failing between services
Services within a Fly organization communicate via <app>.internal hostnames, but AI-generated code hardcodes localhost or public URLs.
Start with a self-serve audit
Get a professional review of your JavaScript project before deploying to Fly.io.
External Security Scan
Black-box review of your public-facing app. No code access needed.
- OWASP Top 10 vulnerability check
- SSL/TLS configuration analysis
- Security header assessment
- Expert review within 24h
Code Audit
In-depth review of your source code for security, quality, and best practices.
- Security vulnerability analysis
- Code quality review
- Dependency audit
- Architecture review
- Expert + AI code analysis
Complete Bundle
Both scans in one package with cross-referenced findings.
- Everything in both products
- Cross-referenced findings
- Unified action plan
100% credited toward any paid service. Start with an audit, then let us fix what we find.
How it works
Tell us about your app
Share your project details and what you need help with.
Expert + AI audit
A human expert assisted by AI reviews your code within 24 hours.
Launch with confidence
We fix what needs fixing and stick around to help.
Frequently asked questions
How do I deploy a JavaScript app to Fly.io?
We handle JavaScript deployments to Fly.io end to end. Start with our code audit ($19) to identify deployment blockers specific to your JavaScript project, then we configure Fly.io, fix issues, and get your app live in production.
What JavaScript issues affect Fly.io deployments?
JavaScript projects commonly have prototype pollution and loose equality comparisons. On Fly.io, these combine with dockerfile missing or misconfigured and volume only available in a single region to cause deployment failures.
Can SpringCode deploy my JavaScript project to Fly.io?
Yes. We specialize in deploying JavaScript applications to Fly.io. We audit your codebase for JavaScript-specific issues, configure Fly.io correctly, and handle the full deployment so your app runs reliably in production.
What does JavaScript deployment to Fly.io cost?
Our code audit ($19) identifies all Fly.io deployment blockers in your JavaScript project. Full deployment assistance is scoped with a fixed quote after the audit — no hourly billing or surprise charges.
Related resources
Other techs on Fly.io
Deploy JavaScript elsewhere
Need help deploying JavaScript to Fly.io?
Tell us about your project. We'll respond within 24 hours with a clear plan and fixed quote.