Go · snapshot 2026-07-sample

We counted every function call across open-source Go.

384,210 calls type-checked across open-source Go. Every dot is a function. Hover one, or search to light up the field.

heaviest in a looperrors.New · 1,751 in-loop calls

Sample data. This build ships the bundled fixture set. A real snapshot replaces it once the pipeline runs.

the ranking

The functions Go actually runs.

Ranked by production calls, what runs outside tests and generated code. Switch to breadth to rank by how many distinct modules reach for a function instead. Page through all 41; open any row for that function.

Origin

Package

Rank by

Export CSV

All Std lib Third-party

Exports are CC BY 4.0. Cite callcount 2026-07-sample.

Ranks 1–41 of 41, by production calls

#	Function
1	fmt.Errorfstd	8,402	8,730	18%	191
2	fmt.Sprintfstd	7,511	9,820	11%	194
3	errors.Newstd	5,590	6,210	31%	125
4	strings.Containsstd	3,711	4,120	27%	203
5	strings.TrimSpacestd	3,393	3,860	35%	215
6	strings.Splitstd	2,984	3,540	25%	189
7	context.WithValuestd	2,660	2,980	17%	73
8	strings.HasPrefixstd	2,526	2,870	33%	103
9	strings.Builder.WriteStringstd	2,231	2,610	30%	60
10	fmt.Fprintfstd	2,112	2,450	18%	142
11	strconv.Itoastd	1,895	2,290	12%	236
12	bytes.Buffer.WriteStringstd	1,785	2,110	19%	99
13	sirupsen/logrus.WithFieldext	1,669	1,830	22%	96
14	sync.Mutex.Lockstd	1,486	1,870	34%	201
15	encoding/json.Marshalstd	1,470	1,690	12%	226
16	reflect.TypeOfstd	1,312	1,980	24%	116
17	regexp.MustCompilestd	1,311	1,740	5%	224
18	strconv.ParseIntstd	1,137	1,520	12%	168
19	sort.Slicestd	1,115	1,410	20%	116
20	time.Nowstd	1,085	1,240	6%	219
21	io.Writer.Writestd	1,039	1,360	15%	148
22	io.Reader.Readstd	1,024	1,180	18%	134
23	regexp.Regexp.MatchStringstd	1,010	1,280	36%	88
24	error.Errorstd	902	1,010	9%	152
25	sync.WaitGroup.Addstd	869	1,180	26%	61
26	net/http.NewRequeststd	809	1,090	6%	140
27	encoding/json.Unmarshalstd	804	1,020	18%	214
28	apimachinery/pkg/util/sets.Newext	799	980	36%	44
29	path/filepath.Joinstd	767	970	14%	84
30	fmt.Stringer.Stringstd	704	812	17%	121
31	spf13/cobra.Command.Flagsext	652	760	13%	38
32	protobuf/proto.Marshalext	642	1,240	19%	61
33	context.Context.Donestd	628	860	25%	108
34	os.Getenvstd	580	910	24%	205
35	bufio.Scanner.Scanstd	561	720	65%	90
36	strings.Joinstd	522	690	30%	184
37	sort.Interface.Lessstd	402	448	47%	74
38	gopkg.in/yaml.v2.Unmarshalext	300	340	10%	12
39	stretchr/testify/assert.Equalext	0	5,140	0%	168
40	stretchr/testify/require.NoErrorext	0	4,620	0%	173
41	stretchr/testify/assert.NoErrorext	0	3,210	0%	151

explore

Two more ways to read the data.

map

Where optimization pays

Plot every function by call volume against loop share. Filter by notable project to see what Kubernetes or Docker runs hot.

interfaces

The interfaces Go dispatches through

The methods most calls dispatch through an interface, like io.Writer.Write and error.Error, counted as their own lens.