Proto3 Declaration Inspector

• Enter values using the examples, or choose a local file where requested. Follow the displayed supported input shapes and limits.
• Choose Calculate result and inspect the complete result.
• Download result to save the primary file. Where supplied, additional links save source files and the full JSON report. Reset restores examples and clears output.

Proto3 source: syntax = "proto3"; package demo; message User { string name = 1; int32 age = 2; }

• Explicit local Proto3 declarations:required leading proto3 syntax,single package,messages/nested types,scalar or resolvable local message/enum fields,singular/optional/repeated,map,nonempty oneof,zero-first enums,reserved names/ranges,and unary/streaming RPC signatures. Resolve local type scopes;check declared names,field numbers/default JSON-name collisions,reservations and enum values. Comments and decimal/octal/hex integers supported. Quoted syntax/reserved names must be simple and unescaped. Refuse imports,options,extensions,editions,enum aliases,overlapping reservations,unsupported constructs and unresolved types. No binary encoding,code generation,external resolution or blanket compiler equivalence. At most20000 tokens/40 nested messages/100000 source UTF16 units;shared output budget applies.
• Text fields are limited to100,000 UTF16 units each and400,000 combined UTF8 bytes; file fields have their own displayed limits. Combined output is at most4MiB. Processing stops after30 seconds; tool-specific bounds may be tighter.
• Generated source is a downloadable result and is not executed here. Inspection does not establish remote behavior, trust or standards certification.