TensorFlow GraphDef, field by field

The whole file is one GraphDef. These messages are from TensorFlow’s graph.proto, versions.proto, function.proto and op_def.proto (syntax = "proto3", package tensorflow, as on TensorFlow’s master branch in November 2026). A frozen graph holds its computation, weights included, as nodes; the function library holds any functions those nodes call. For the bytes of tags and lengths, see the Protocol Buffers reference.

GraphDef

A graph of operations: the nodes, the graph’s versions and a library of functions.

Field	Name	Type	Wire type	Meaning
1	`node`	repeated NodeDef	LEN, one per node	The nodes, in any order; inputs are by name.
4	`versions`	VersionDef	LEN	The GraphDef version of the program that wrote it, and the oldest that can read it.
3	`version`	int32	VARINT	Deprecated and ignored; use `versions`.
2	`library`	FunctionDefLibrary	LEN	Functions the graph calls.
5	`debug_info`	GraphDebugInfo	LEN	Stack traces for the nodes. The explorer does not include this message and shows it by number.

A complete 56-byte frozen graph, built for this page: one Const node named w holding the two floats 1.0 and 2.0.

0A 36 0A 01 77 12 05 43 6F 6E 73 74 2A 0B 0A 05 64 74 79 70 65 12 02 30 01
2A 1D 0A 05 76 61 6C 75 65 12 14 42 12 08 01 12 04 12 02 08 02 22 08 00 00 80 3F 00 00 00 40

Field 1, node, 54 bytes: a NodeDef with name, op and two attributes

The node is decoded field by field on NodeDef and attributes. A real frozen graph has many such nodes, with their inputs, and usually a versions field.

VersionDef

Versions of the GraphDef format, which rise with TensorFlow releases. Which release gives which number was not researched for this page.

Field	Name	Type	Wire type	Meaning
1	`producer`	int32	VARINT	The GraphDef version of the program that wrote it.
2	`min_consumer`	int32	VARINT	The oldest GraphDef version that can read it.
3	`bad_consumers`	repeated int32, packed	LEN	Versions that must not read it.

FunctionDefLibrary

Field	Name	Type	Wire type	Meaning
1	`function`	repeated FunctionDef	LEN, one per function	The functions.
2	`gradient`	repeated GradientDef	LEN, one per entry	Which function is the gradient of which.
3	`registered_gradients`	repeated RegisteredGradient	LEN, one per entry	Gradients registered for op types.

FunctionDef

A function: its signature, its body of nodes, and where its outputs come from. A node calls it by giving the function’s name as its op.

Field	Name	Type	Wire type	Meaning
1	`signature`	OpDef	LEN	The function’s name, arguments and attributes.
5	`attr`	map<string, AttrValue>	LEN, one per entry	Attributes of the function itself.
7	`arg_attr`	map<uint32, ArgAttrs>	LEN, one per entry	Attributes of each argument, by index.
8	`resource_arg_unique_id`	map<uint32, uint32>	LEN, one per entry	Which resource arguments refer to the same resource.
3	`node_def`	repeated NodeDef	LEN, one per node	The body. Inside a function, inputs may name a node’s output by its output argument, as `node:arg:0`.
4	`ret`	map<string, string>	LEN, one per entry	Which node output each output of the function is.
6	`control_ret`	map<string, string>	LEN, one per entry	Control outputs: which node each names.

Field 2 is reserved.

FunctionDef.AttrEntry

Field	Name	Type	Wire type	Meaning
1	`key`	string	LEN	The attribute’s name.
2	`value`	AttrValue	LEN	Its value.

FunctionDef.ArgAttrEntry

Field	Name	Type	Wire type	Meaning
1	`key`	uint32	VARINT	The argument’s index.
2	`value`	ArgAttrs	LEN	Its attributes.

FunctionDef.ArgAttrs

Field	Name	Type	Wire type	Meaning
1	`attr`	map<string, AttrValue>	LEN, one per entry	The attributes of one argument.

FunctionDef.ArgAttrs.AttrEntry

Field	Name	Type	Wire type	Meaning
1	`key`	string	LEN	The attribute’s name.
2	`value`	AttrValue	LEN	Its value.

FunctionDef.ResourceArgUniqueIdEntry

Field	Name	Type	Wire type	Meaning
1	`key`	uint32	VARINT	An argument’s index.
2	`value`	uint32	VARINT	Its resource’s ID.

FunctionDef.RetEntry

Field	Name	Type	Wire type	Meaning
1	`key`	string	LEN	An output argument’s name.
2	`value`	string	LEN	The node output it comes from.

FunctionDef.ControlRetEntry

Field	Name	Type	Wire type	Meaning
1	`key`	string	LEN	A control output’s name.
2	`value`	string	LEN	The node it names.

GradientDef

Field	Name	Type	Wire type	Meaning
1	`function_name`	string	LEN	A function in the library.
2	`gradient_func`	string	LEN	The function that computes its gradient.

RegisteredGradient

Field	Name	Type	Wire type	Meaning
1	`gradient_func`	string	LEN	The gradient function.
2	`registered_op_type`	string	LEN	The op type it is registered for.

OpDef

An op’s or a function’s signature: its name, arguments, attributes and flags. In a GraphDef it appears as the signature of each function.

Field	Name	Type	Wire type	Meaning
1	`name`	string	LEN	The name.
2	`input_arg`	repeated ArgDef	LEN, one per argument	Inputs.
3	`output_arg`	repeated ArgDef	LEN, one per argument	Outputs.
20	`control_output`	repeated string	LEN, one per name	Control outputs.
4	`attr`	repeated AttrDef	LEN, one per attribute	Attributes it takes.
8	`deprecation`	OpDeprecation	LEN	When it was deprecated.
5	`summary`	string	LEN	A one-line summary.
6	`description`	string	LEN	A description.
18	`is_commutative`	bool	VARINT	Whether the inputs can be swapped.
16	`is_aggregate`	bool	VARINT	Whether it adds up its inputs.
17	`is_stateful`	bool	VARINT	Whether it has state.
19	`allows_uninitialized_input`	bool	VARINT	Whether inputs may be uninitialised.
21	`is_distributed_communication`	bool	VARINT	Whether it communicates between devices.

OpDef.ArgDef

One argument. Its type is fixed by type, or named by one of the *_attr fields.

Field	Name	Type	Wire type	Meaning
1	`name`	string	LEN	The name.
2	`description`	string	LEN	A description.
3	`type`	DataType	VARINT	A fixed data type.
4	`type_attr`	string	LEN	The attribute that holds its type.
5	`number_attr`	string	LEN	The attribute that holds how many there are.
6	`type_list_attr`	string	LEN	The attribute that holds a list of types.
7	`handle_data`	repeated DtypeAndShape	LEN, one per entry	For resources: what they hold.
16	`is_ref`	bool	VARINT	Whether it is a reference.
17	`experimental_full_type`	FullTypeDef	LEN	Its full type; shown by number.

OpDef.AttrDef

One attribute an op takes.

Field	Name	Type	Wire type	Meaning
1	`name`	string	LEN	The name.
2	`type`	string	LEN	Its type as text, such as `int`, `type` or `list(type)`.
3	`default_value`	AttrValue	LEN	Its default.
4	`description`	string	LEN	A description.
5	`has_minimum`	bool	VARINT	Whether it has a minimum.
6	`minimum`	int64	VARINT	The minimum.
7	`allowed_values`	AttrValue	LEN	The values allowed, as a list.

OpDeprecation

Field	Name	Type	Wire type	Meaning
1	`version`	int32	VARINT	The GraphDef version from which the op is deprecated.
2	`explanation`	string	LEN	Why, and what to use instead.

OpList

A list of op definitions. A GraphDef does not hold one itself; it is part of the schema the parser reads, used where TensorFlow lists the ops a graph needs.

Field	Name	Type	Wire type	Meaning
1	`op`	repeated OpDef	LEN, one per op	The ops.

.PB File Format – GraphDef