Migration target
Migrate VB6 to C#, without a big-bang rewrite.
C# is a natural landing spot for a VB6 codebase — same .NET-adjacent COM heritage, a language your remaining engineers can actually staff for. UnspoolCode translates out of the same dependency graph it uses for analysis, batch by batch, in dependency order, with a COM interop bridge so the parts you haven't migrated yet keep working.
Pre-GA · early access is by waitlist · no spam, ever.
01Why C#
Why teams pick C# over a from-scratch rewrite
Staffable
A shrinking pool of engineers can read VB6. A much larger pool can read and write C# — that's who you're hiring for the next decade of this system's life.
COM-compatible mid-transition
You don't have to migrate everything at once. Migrated code can still call back into VB6 COM components you haven't gotten to yet.
"Just rewrite it" dies in committee
Nobody can prove a ground-up rewrite behaves like the original before cutover. Batch translation out of the real dependency graph gives you something to verify against, unit by unit.
02How it works
Snapshot, translate, shim, verify, mark, done — per unit
draft_plan computes migration units and their dependency order from the graph, thenbatch_start runs them through a scheduler that resumes cleanly after a restart. Every low-confidence translation routes through a review queue — approve it, reject it, or submit your own — before it can pass verify. Destructive edits sit behind an explicit preview-then-confirm step; direct writes are hash-checked against the last-read source to catch anything stale.
COM interop bridge
The C# target generates a COM-visible interop bridge — ComVisible attributes, deterministic GUIDs/ProgIds — so migrated code can call back into VB6 COM components you haven't migrated yet. It compiles clean today; full Windows-side COM activation and VB6 round-trip call-parity verification is in progress.
Measured, not estimated
338 units drafted on a real project in 7.2s. Service RSS across a full batch run: 519MB. Same graph, same tools, same numbers published on themeasured scale section.
03Scope
What's covered today, and what's still in progress
Translation compiles clean today. Full Windows-side COM activation and VB6 round-trip call-parity verification — confirming a migrated component genuinely behaves like its VB6 original when called from a real VB6 caller at runtime — is still in progress. Review every finding, every generated graph edge, and every line of generated code against your own engineering judgement and testing before relying on it in production. See the source language and file-type details on thelanguages page, or theterms of service for the full advisory.
Early access
Be first to run it on your codebase.
UnspoolCode is real, working software, currently pre-GA. Join the waitlist and we'll reach out when early access opens — no commitment, no spam.