diff --git a/lib/gcpspanner/missing_one_implementation.go b/lib/gcpspanner/missing_one_implementation.go
new file mode 100644
index 00000000..c637b2e4
--- /dev/null
+++ b/lib/gcpspanner/missing_one_implementation.go
@@ -0,0 +1,224 @@
+// Copyright 2024 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package gcpspanner
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"time"
+
+	"cloud.google.com/go/spanner"
+	"google.golang.org/api/iterator"
+)
+
+func init() {
+	missingOneImplTemplate = NewQueryTemplate(missingOneImplCountRawTemplate)
+}
+
+// nolint: gochecknoglobals // WONTFIX. Compile the template once at startup. Startup fails if invalid.
+var (
+	// missingOneImplTemplate is the compiled version of missingOneImplCountRawTemplate.
+	missingOneImplTemplate BaseQueryTemplate
+)
+
+// MissingOneImplCountPage contains the details for the missing one implementation count request.
+type MissingOneImplCountPage struct {
+	NextPageToken *string
+	Metrics       []MissingOneImplCount
+}
+
+// spannerMissingOneImplCount is a wrapper for the missing one implementation count.
+type spannerMissingOneImplCount struct {
+	MissingOneImplCount
+}
+
+// MissingOneImplCount contains information regarding the count of features implemented in all other browsers but not
+// in the target browser.
+type MissingOneImplCount struct {
+	EventReleaseDate time.Time `spanner:"EventReleaseDate"`
+	Count            int64     `spanner:"Count"`
+}
+
+// missingOneImplCursor: Represents a point for resuming queries based on the last
+// browser release date. Useful for pagination.
+type missingOneImplCursor struct {
+	ReleaseDate time.Time `json:"release_date"`
+}
+
+// decodeMissingOneImplCursor provides a wrapper around the generic decodeCursor.
+func decodeMissingOneImplCursor(cursor string) (*missingOneImplCursor, error) {
+	return decodeCursor[missingOneImplCursor](cursor)
+}
+
+// encodeMissingOneImplCursor provides a wrapper around the generic encodeCursor.
+func encodeMissingOneImplCursor(releaseDate time.Time) string {
+	return encodeCursor(missingOneImplCursor{
+		ReleaseDate: releaseDate,
+	})
+}
+
+const missingOneImplCountRawTemplate = `
+SELECT releases.EventReleaseDate,
+       (
+           SELECT COUNT(DISTINCT wf.ID)
+           FROM WebFeatures wf
+           LEFT JOIN BrowserFeatureSupportEvents bfse
+               ON wf.ID = bfse.WebFeatureID
+			   AND bfse.TargetBrowserName = @targetBrowserParam
+               AND bfse.EventReleaseDate = releases.EventReleaseDate
+               AND bfse.SupportStatus = 'unsupported'  -- Added condition
+           WHERE bfse.WebFeatureID IS NOT NULL  -- Feature is unsupported by the target browser
+             AND {{range $browser := .OtherBrowserParamNames}}
+                 EXISTS (
+                   SELECT 1
+                   FROM BrowserFeatureSupportEvents bfse_other
+                   WHERE bfse_other.WebFeatureID = wf.ID
+                     AND bfse_other.SupportStatus = 'supported'
+                     AND bfse_other.TargetBrowserName = @{{ $browser }}
+                     AND bfse_other.EventReleaseDate = releases.EventReleaseDate
+                 )
+                 AND
+               {{end}}
+			   1=1
+       ) AS Count
+FROM (
+    SELECT DISTINCT EventReleaseDate
+    FROM BrowserFeatureSupportEvents
+    WHERE TargetBrowserName = @targetBrowserParam
+		AND EventBrowserName IN UNNEST(@allBrowsersParam)
+) releases
+WHERE releases.EventReleaseDate >= @startAt
+  AND releases.EventReleaseDate < @endAt
+  {{if .ReleaseDateParam }}
+  AND releases.EventReleaseDate < @{{ .ReleaseDateParam }}
+  {{end}}
+ORDER BY releases.EventReleaseDate DESC
+LIMIT @limit;
+`
+
+type missingOneImplTemplateData struct {
+	OtherBrowserParamNames []string
+	ReleaseDateParam       string
+}
+
+func buildMissingOneImplTemplate(
+	cursor *missingOneImplCursor,
+	targetBrowser string,
+	otherBrowsers []string,
+	startAt time.Time,
+	endAt time.Time,
+	pageSize int,
+) spanner.Statement {
+	params := map[string]interface{}{}
+	allBrowsers := make([]string, len(otherBrowsers)+1)
+	copy(allBrowsers, otherBrowsers)
+	allBrowsers[len(allBrowsers)-1] = targetBrowser
+	params["targetBrowserParam"] = targetBrowser
+	params["allBrowsersParam"] = allBrowsers
+	otherBrowsersParamNames := make([]string, 0, len(otherBrowsers))
+	for i := range otherBrowsers {
+		paramName := fmt.Sprintf("otherBrowser%d", i)
+		params[paramName] = otherBrowsers[i]
+		otherBrowsersParamNames = append(otherBrowsersParamNames, paramName)
+	}
+	params["limit"] = pageSize
+
+	releaseDateParamName := ""
+	if cursor != nil {
+		releaseDateParamName = "releaseDateCursor"
+		params[releaseDateParamName] = cursor.ReleaseDate
+	}
+
+	params["startAt"] = startAt
+	params["endAt"] = endAt
+
+	tmplData := missingOneImplTemplateData{
+		OtherBrowserParamNames: otherBrowsersParamNames,
+		ReleaseDateParam:       releaseDateParamName,
+	}
+	sql := missingOneImplTemplate.Execute(tmplData)
+	stmt := spanner.NewStatement(sql)
+	stmt.Params = params
+
+	return stmt
+}
+
+func (c *Client) ListMissingOneImplCounts(
+	ctx context.Context,
+	targetBrowser string,
+	otherBrowsers []string,
+	startAt time.Time,
+	endAt time.Time,
+	pageSize int,
+	pageToken *string,
+) (*MissingOneImplCountPage, error) {
+
+	var cursor *missingOneImplCursor
+	var err error
+	if pageToken != nil {
+		cursor, err = decodeMissingOneImplCursor(*pageToken)
+		if err != nil {
+			return nil, errors.Join(ErrInternalQueryFailure, err)
+		}
+	}
+
+	txn := c.ReadOnlyTransaction()
+	defer txn.Close()
+
+	stmt := buildMissingOneImplTemplate(
+		cursor,
+		targetBrowser,
+		otherBrowsers,
+		startAt,
+		endAt,
+		pageSize,
+	)
+
+	it := txn.Query(ctx, stmt)
+	defer it.Stop()
+
+	var results []MissingOneImplCount
+	for {
+		row, err := it.Next()
+		if errors.Is(err, iterator.Done) {
+			break
+		}
+		if err != nil {
+			return nil, err
+		}
+		var result spannerMissingOneImplCount
+		if err := row.ToStruct(&result); err != nil {
+			return nil, err
+		}
+		actualResult := MissingOneImplCount{
+			EventReleaseDate: result.EventReleaseDate,
+			Count:            result.Count,
+		}
+		results = append(results, actualResult)
+	}
+
+	page := MissingOneImplCountPage{
+		Metrics:       results,
+		NextPageToken: nil,
+	}
+
+	if len(results) == pageSize {
+		token := encodeMissingOneImplCursor(results[len(results)-1].EventReleaseDate)
+		page.NextPageToken = &token
+	}
+
+	return &page, nil
+}
diff --git a/lib/gcpspanner/missing_one_implementation_test.go b/lib/gcpspanner/missing_one_implementation_test.go
new file mode 100644
index 00000000..939a9855
--- /dev/null
+++ b/lib/gcpspanner/missing_one_implementation_test.go
@@ -0,0 +1,668 @@
+// Copyright 2024 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package gcpspanner
+
+import (
+	"context"
+	"reflect"
+	"slices"
+	"testing"
+	"time"
+)
+
+func loadDataForListMissingOneImplCounts(ctx context.Context, t *testing.T, client *Client) {
+	webFeatures := []WebFeature{
+		{FeatureKey: "FeatureX", Name: "Cool API"},
+		{FeatureKey: "FeatureY", Name: "Super API"},
+		{FeatureKey: "FeatureZ", Name: "Neat API"},
+		{FeatureKey: "FeatureW", Name: "Amazing API"},
+	}
+	for _, feature := range webFeatures {
+		_, err := client.UpsertWebFeature(ctx, feature)
+		if err != nil {
+			t.Errorf("unexpected error during insert of features. %s", err.Error())
+		}
+	}
+
+	browserReleases := []BrowserRelease{
+		// fooBrowser Releases
+		{BrowserName: "fooBrowser", BrowserVersion: "110", ReleaseDate: time.Date(2024, 1, 10, 0, 0, 0, 0, time.UTC)},
+		{BrowserName: "fooBrowser", BrowserVersion: "111", ReleaseDate: time.Date(2024, 2, 1, 0, 0, 0, 0, time.UTC)},
+		{BrowserName: "fooBrowser", BrowserVersion: "112", ReleaseDate: time.Date(2024, 3, 15, 0, 0, 0, 0, time.UTC)},
+		{BrowserName: "fooBrowser", BrowserVersion: "113", ReleaseDate: time.Date(2024, 4, 15, 0, 0, 0, 0, time.UTC)},
+
+		// barBrowser Releases
+		{BrowserName: "barBrowser", BrowserVersion: "113", ReleaseDate: time.Date(2024, 1, 20, 0, 0, 0, 0, time.UTC)},
+		{BrowserName: "barBrowser", BrowserVersion: "114", ReleaseDate: time.Date(2024, 3, 28, 0, 0, 0, 0, time.UTC)},
+		{BrowserName: "barBrowser", BrowserVersion: "115", ReleaseDate: time.Date(2024, 4, 1, 0, 0, 0, 0, time.UTC)},
+
+		// bazBrowser Releases
+		{BrowserName: "bazBrowser", BrowserVersion: "16.4", ReleaseDate: time.Date(2024, 1, 25, 0, 0, 0, 0, time.UTC)},
+		{BrowserName: "bazBrowser", BrowserVersion: "16.5", ReleaseDate: time.Date(2024, 3, 5, 0, 0, 0, 0, time.UTC)},
+		{BrowserName: "bazBrowser", BrowserVersion: "17", ReleaseDate: time.Date(2024, 4, 1, 0, 0, 0, 0, time.UTC)},
+	}
+	for _, release := range browserReleases {
+		err := client.InsertBrowserRelease(ctx, release)
+		if err != nil {
+			t.Errorf("unexpected error during insert of releases. %s", err.Error())
+		}
+	}
+
+	browserFeatureAvailabilities := []struct {
+		FeatureKey string
+		BrowserFeatureAvailability
+	}{
+		// fooBrowser Availabilities
+		{
+			BrowserFeatureAvailability: BrowserFeatureAvailability{BrowserName: "fooBrowser", BrowserVersion: "111"},
+			FeatureKey:                 "FeatureX",
+		}, // Available from fooBrowser 111
+		{
+			BrowserFeatureAvailability: BrowserFeatureAvailability{BrowserName: "fooBrowser", BrowserVersion: "112"},
+			FeatureKey:                 "FeatureY",
+		}, // Available from fooBrowser 112
+		{
+			BrowserFeatureAvailability: BrowserFeatureAvailability{BrowserName: "fooBrowser", BrowserVersion: "112"},
+			FeatureKey:                 "FeatureZ",
+		}, // Available from fooBrowser 112
+		{
+			BrowserFeatureAvailability: BrowserFeatureAvailability{BrowserName: "fooBrowser", BrowserVersion: "113"},
+			FeatureKey:                 "FeatureW",
+		}, // Available from fooBrowser 113
+
+		// barBrowser Availabilities
+		{
+			BrowserFeatureAvailability: BrowserFeatureAvailability{BrowserName: "barBrowser", BrowserVersion: "113"},
+			FeatureKey:                 "FeatureX",
+		}, // Available from barBrowser 113
+		{
+			BrowserFeatureAvailability: BrowserFeatureAvailability{BrowserName: "barBrowser", BrowserVersion: "113"},
+			FeatureKey:                 "FeatureZ",
+		}, // Available from barBrowser 113
+		{
+			BrowserFeatureAvailability: BrowserFeatureAvailability{BrowserName: "barBrowser", BrowserVersion: "114"},
+			FeatureKey:                 "FeatureY",
+		}, // Available from barBrowser 114
+		{
+			BrowserFeatureAvailability: BrowserFeatureAvailability{BrowserName: "barBrowser", BrowserVersion: "115"},
+			FeatureKey:                 "FeatureW",
+		}, // Available from barBrowser 115
+
+		// bazBrowser Availabilities
+		{
+			BrowserFeatureAvailability: BrowserFeatureAvailability{BrowserName: "bazBrowser", BrowserVersion: "16.4"},
+			FeatureKey:                 "FeatureX",
+		}, // Available from bazBrowser 16.4
+		{
+			BrowserFeatureAvailability: BrowserFeatureAvailability{BrowserName: "bazBrowser", BrowserVersion: "16.5"},
+			FeatureKey:                 "FeatureY",
+		}, // Available from bazBrowser 16.5
+	}
+	for _, availability := range browserFeatureAvailabilities {
+		err := client.InsertBrowserFeatureAvailability(ctx,
+			availability.FeatureKey, availability.BrowserFeatureAvailability)
+		if err != nil {
+			t.Errorf("unexpected error during insert. %s", err.Error())
+		}
+	}
+	err := spannerClient.PrecalculateBrowserFeatureSupportEvents(ctx)
+	if err != nil {
+		t.Errorf("unexpected error during pre-calculate. %s", err.Error())
+	}
+}
+
+func assertListMissingOneImplCounts(ctx context.Context, t *testing.T, startAt, endAt time.Time, pageToken *string,
+	targetBrowser string, otherBrowsers []string, pageSize int, expectedPage *MissingOneImplCountPage) {
+	result, err := spannerClient.ListMissingOneImplCounts(
+		ctx,
+		targetBrowser,
+		otherBrowsers,
+		startAt,
+		endAt,
+		pageSize,
+		pageToken,
+	)
+	if err != nil {
+		t.Errorf("Unexpected error: %v", err)
+	}
+	if !reflect.DeepEqual(expectedPage, result) {
+		t.Errorf("unexpected result.\nExpected %+v\nReceived %+v", expectedPage, result)
+	}
+}
+
+func TestListMissingOneImplCounts(t *testing.T) {
+	restartDatabaseContainer(t)
+	ctx := context.Background()
+
+	loadDataForListMissingOneImplCounts(ctx, t, spannerClient)
+	actualEvents := spannerClient.readAllBrowserFeatureSupportEvents(ctx, t)
+	slices.SortFunc(actualEvents, sortBrowserFeatureSupportEvents)
+	defaultStartAt := time.Date(2020, 1, 1, 0, 0, 0, 0, time.UTC)
+	defaultEndAt := time.Date(2025, 1, 1, 0, 0, 0, 0, time.UTC)
+	defaultPageSize := 100
+
+	t.Run("bazBrowser ", func(t *testing.T) {
+		targetBrowser := "bazBrowser"
+		otherBrowsers := []string{
+			"fooBrowser",
+			"barBrowser",
+		}
+
+		// nolint:dupl // WONTFIX - false positive
+		t.Run("all data in one page", func(t *testing.T) {
+			expectedResult := &MissingOneImplCountPage{
+				NextPageToken: nil,
+				Metrics: []MissingOneImplCount{
+					// fooBrowser 113 release
+					// Currently supported features:
+					// fooBrowser: FeatureX, FeatureZ, FeatureY, FeatureW
+					// barBrowser: FeatureX, FeatureZ, FeatureY, FeatureW
+					// bazBrowser: FeatureX, FeatureY
+					// Missing in on for bazBrowser: FeatureW, FeatureZ
+					{
+						EventReleaseDate: time.Date(2024, 4, 15, 0, 0, 0, 0, time.UTC),
+						Count:            2,
+					},
+					// barBrowser 115 AND bazBrowser 17 release
+					// Currently supported features:
+					// fooBrowser: FeatureX, FeatureZ, FeatureY
+					// barBrowser: FeatureX, FeatureZ, FeatureY, FeatureW
+					// bazBrowser: FeatureX, FeatureY
+					// Missing in on for bazBrowser: FeatureZ
+					{
+						EventReleaseDate: time.Date(2024, 4, 1, 0, 0, 0, 0, time.UTC),
+						Count:            1,
+					},
+					// barBrowser 114 release
+					// Currently supported features:
+					// fooBrowser: FeatureX, FeatureZ, FeatureY
+					// barBrowser: FeatureX, FeatureZ, FeatureY
+					// bazBrowser: FeatureX, FeatureY
+					// Missing in on for bazBrowser: FeatureZ
+					{
+						EventReleaseDate: time.Date(2024, 3, 28, 0, 0, 0, 0, time.UTC),
+						Count:            1,
+					},
+					// fooBrowser 112 release
+					// Currently supported features:
+					// fooBrowser: FeatureX, FeatureY, FeatureZ
+					// barBrowser: FeatureX, FeatureZ
+					// bazBrowser: FeatureX, FeatureY
+					// Missing in on for bazBrowser: FeatureZ
+					{
+						EventReleaseDate: time.Date(2024, 3, 15, 0, 0, 0, 0, time.UTC),
+						Count:            1,
+					},
+					// bazBrowser 16.5 release
+					// Currently supported features:
+					// fooBrowser: FeatureX
+					// barBrowser: FeatureX, FeatureZ
+					// bazBrowser: FeatureX, FeatureY
+					// Missing in on for bazBrowser: None
+					{
+						EventReleaseDate: time.Date(2024, 3, 5, 0, 0, 0, 0, time.UTC),
+						Count:            0,
+					},
+					// fooBrowser 111 release
+					// Currently supported features:
+					// fooBrowser: FeatureX
+					// barBrowser: FeatureX, FeatureZ
+					// bazBrowser: FeatureX
+					// Missing in on for bazBrowser: None
+					{
+						EventReleaseDate: time.Date(2024, 2, 1, 0, 0, 0, 0, time.UTC),
+						Count:            0,
+					},
+					// bazBrowser 16.4 release
+					// Currently supported features:
+					// fooBrowser: None
+					// barBrowser: FeatureX, FeatureZ
+					// bazBrowser: FeatureX
+					// Missing in on for bazBrowser: None
+					{
+						EventReleaseDate: time.Date(2024, 1, 25, 0, 0, 0, 0, time.UTC),
+						Count:            0,
+					},
+					// barBrowser 113 release
+					// Currently supported features:
+					// fooBrowser: None
+					// barBrowser: FeatureX, FeatureZ
+					// bazBrowser: None
+					// Missing in on for bazBrowser: None
+					{
+						EventReleaseDate: time.Date(2024, 1, 20, 0, 0, 0, 0, time.UTC),
+						Count:            0,
+					},
+					// fooBrowser 110 release
+					// Currently supported features:
+					// fooBrowser: None
+					// barBrowser: None
+					// bazBrowser: None
+					// Missing in on for bazBrowser: None
+					{
+						EventReleaseDate: time.Date(2024, 1, 10, 0, 0, 0, 0, time.UTC),
+						Count:            0,
+					},
+				},
+			}
+			assertListMissingOneImplCounts(
+				ctx,
+				t,
+				defaultStartAt,
+				defaultEndAt,
+				nil,
+				targetBrowser,
+				otherBrowsers,
+				defaultPageSize,
+				expectedResult,
+			)
+		})
+
+		t.Run("pagination", func(t *testing.T) {
+			// Page One
+			pageOneToken := encodeMissingOneImplCursor(time.Date(2024, 3, 15, 0, 0, 0, 0, time.UTC))
+			expectedPageOne := &MissingOneImplCountPage{
+				NextPageToken: &pageOneToken,
+				Metrics: []MissingOneImplCount{
+					// fooBrowser 113 release
+					// Currently supported features:
+					// fooBrowser: FeatureX, FeatureZ, FeatureY, FeatureW
+					// barBrowser: FeatureX, FeatureZ, FeatureY, FeatureW
+					// bazBrowser: FeatureX, FeatureY
+					// Missing in on for bazBrowser: FeatureW, FeatureZ
+					{
+						EventReleaseDate: time.Date(2024, 4, 15, 0, 0, 0, 0, time.UTC),
+						Count:            2,
+					},
+					// barBrowser 115 AND bazBrowser 17 release
+					// Currently supported features:
+					// fooBrowser: FeatureX, FeatureZ, FeatureY
+					// barBrowser: FeatureX, FeatureZ, FeatureY, FeatureW
+					// bazBrowser: FeatureX, FeatureY
+					// Missing in on for bazBrowser: FeatureZ
+					{
+						EventReleaseDate: time.Date(2024, 4, 1, 0, 0, 0, 0, time.UTC),
+						Count:            1,
+					},
+					// barBrowser 114 release
+					// Currently supported features:
+					// fooBrowser: FeatureX, FeatureZ, FeatureY
+					// barBrowser: FeatureX, FeatureZ, FeatureY
+					// bazBrowser: FeatureX, FeatureY
+					// Missing in on for bazBrowser: FeatureZ
+					{
+						EventReleaseDate: time.Date(2024, 3, 28, 0, 0, 0, 0, time.UTC),
+						Count:            1,
+					},
+					// fooBrowser 112 release
+					// Currently supported features:
+					// fooBrowser: FeatureX, FeatureY, FeatureZ
+					// barBrowser: FeatureX, FeatureZ
+					// bazBrowser: FeatureX, FeatureY
+					// Missing in on for bazBrowser: FeatureZ
+					{
+						EventReleaseDate: time.Date(2024, 3, 15, 0, 0, 0, 0, time.UTC),
+						Count:            1,
+					},
+				},
+			}
+
+			assertListMissingOneImplCounts(
+				ctx,
+				t,
+				defaultStartAt,
+				defaultEndAt,
+				nil,
+				targetBrowser,
+				otherBrowsers,
+				4,
+				expectedPageOne,
+			)
+
+			// Page Two
+			pageTwoToken := encodeMissingOneImplCursor(time.Date(2024, 1, 20, 0, 0, 0, 0, time.UTC))
+			expectedPageTwo := &MissingOneImplCountPage{
+				NextPageToken: &pageTwoToken,
+				Metrics: []MissingOneImplCount{
+					// bazBrowser 16.5 release
+					// Currently supported features:
+					// fooBrowser: FeatureX
+					// barBrowser: FeatureX, FeatureZ
+					// bazBrowser: FeatureX, FeatureY
+					// Missing in on for bazBrowser: None
+					{
+						EventReleaseDate: time.Date(2024, 3, 5, 0, 0, 0, 0, time.UTC),
+						Count:            0,
+					},
+					// fooBrowser 111 release
+					// Currently supported features:
+					// fooBrowser: FeatureX
+					// barBrowser: FeatureX, FeatureZ
+					// bazBrowser: FeatureX
+					// Missing in on for bazBrowser: None
+					{
+						EventReleaseDate: time.Date(2024, 2, 1, 0, 0, 0, 0, time.UTC),
+						Count:            0,
+					},
+					// bazBrowser 16.4 release
+					// Currently supported features:
+					// fooBrowser: None
+					// barBrowser: FeatureX, FeatureZ
+					// bazBrowser: FeatureX
+					// Missing in on for bazBrowser: None
+					{
+						EventReleaseDate: time.Date(2024, 1, 25, 0, 0, 0, 0, time.UTC),
+						Count:            0,
+					},
+					// barBrowser 113 release
+					// Currently supported features:
+					// fooBrowser: None
+					// barBrowser: FeatureX, FeatureZ
+					// bazBrowser: None
+					// Missing in on for bazBrowser: None
+					{
+						EventReleaseDate: time.Date(2024, 1, 20, 0, 0, 0, 0, time.UTC),
+						Count:            0,
+					},
+				},
+			}
+			assertListMissingOneImplCounts(
+				ctx,
+				t,
+				defaultStartAt,
+				defaultEndAt,
+				&pageOneToken,
+				targetBrowser,
+				otherBrowsers,
+				4,
+				expectedPageTwo,
+			)
+
+			// Page Three
+			expectedPageThree := &MissingOneImplCountPage{
+				NextPageToken: nil,
+				Metrics: []MissingOneImplCount{
+					// fooBrowser 110 release
+					// Currently supported features:
+					// fooBrowser: None
+					// barBrowser: None
+					// bazBrowser: None
+					// Missing in on for bazBrowser: None
+					{
+						EventReleaseDate: time.Date(2024, 1, 10, 0, 0, 0, 0, time.UTC),
+						Count:            0,
+					},
+				},
+			}
+			assertListMissingOneImplCounts(
+				ctx,
+				t,
+				defaultStartAt,
+				defaultEndAt,
+				&pageTwoToken,
+				targetBrowser,
+				otherBrowsers,
+				4,
+				expectedPageThree,
+			)
+		})
+
+		t.Run("should reduce the number of results by constraining startAt and endAt", func(t *testing.T) {
+			expectedResult := &MissingOneImplCountPage{
+				NextPageToken: nil,
+				Metrics: []MissingOneImplCount{
+					// barBrowser 114 release
+					// Currently supported features:
+					// fooBrowser: FeatureX, FeatureZ, FeatureY
+					// barBrowser: FeatureX, FeatureZ, FeatureY
+					// bazBrowser: FeatureX, FeatureY
+					// Missing in on for bazBrowser: FeatureZ
+					{
+						EventReleaseDate: time.Date(2024, 3, 28, 0, 0, 0, 0, time.UTC),
+						Count:            1,
+					},
+					// fooBrowser 112 release
+					// Currently supported features:
+					// fooBrowser: FeatureX, FeatureY, FeatureZ
+					// barBrowser: FeatureX, FeatureZ
+					// bazBrowser: FeatureX, FeatureY
+					// Missing in on for bazBrowser: FeatureZ
+					{
+						EventReleaseDate: time.Date(2024, 3, 15, 0, 0, 0, 0, time.UTC),
+						Count:            1,
+					},
+					// bazBrowser 16.5 release
+					// Currently supported features:
+					// fooBrowser: FeatureX
+					// barBrowser: FeatureX, FeatureZ
+					// bazBrowser: FeatureX, FeatureY
+					// Missing in on for bazBrowser: None
+					{
+						EventReleaseDate: time.Date(2024, 3, 5, 0, 0, 0, 0, time.UTC),
+						Count:            0,
+					},
+					// fooBrowser 111 release
+					// Currently supported features:
+					// fooBrowser: FeatureX
+					// barBrowser: FeatureX, FeatureZ
+					// bazBrowser: FeatureX
+					// Missing in on for bazBrowser: None
+					{
+						EventReleaseDate: time.Date(2024, 2, 1, 0, 0, 0, 0, time.UTC),
+						Count:            0,
+					},
+				},
+			}
+			assertListMissingOneImplCounts(
+				ctx,
+				t,
+				time.Date(2024, 2, 1, 0, 0, 0, 0, time.UTC),
+				time.Date(2024, 4, 1, 0, 0, 0, 0, time.UTC),
+				nil,
+				targetBrowser,
+				otherBrowsers,
+				defaultPageSize,
+				expectedResult,
+			)
+		})
+
+		t.Run("should show less data points when looking at a smaller subset of browsers", func(t *testing.T) {
+			otherBrowsers := []string{
+				"barBrowser",
+			}
+
+			expectedResult := &MissingOneImplCountPage{
+				NextPageToken: nil,
+				Metrics: []MissingOneImplCount{
+					// barBrowser 115 AND bazBrowser 17 release
+					// Currently supported features:
+					// barBrowser: FeatureX, FeatureZ, FeatureY, FeatureW
+					// bazBrowser: FeatureX, FeatureY
+					// Missing in on for bazBrowser: FeatureZ, FeatureW
+					{
+						EventReleaseDate: time.Date(2024, 4, 1, 0, 0, 0, 0, time.UTC),
+						Count:            2,
+					},
+					// barBrowser 114 release
+					// Currently supported features:
+					// barBrowser: FeatureX, FeatureZ, FeatureY
+					// bazBrowser: FeatureX, FeatureY
+					// Missing in on for bazBrowser: FeatureZ
+					{
+						EventReleaseDate: time.Date(2024, 3, 28, 0, 0, 0, 0, time.UTC),
+						Count:            1,
+					},
+					// bazBrowser 16.5 release
+					// Currently supported features:
+					// barBrowser: FeatureX, FeatureZ
+					// bazBrowser: FeatureX, FeatureY
+					// Missing in on for bazBrowser: FeatureZ
+					{
+						EventReleaseDate: time.Date(2024, 3, 5, 0, 0, 0, 0, time.UTC),
+						Count:            1,
+					},
+					// bazBrowser 16.4 release
+					// Currently supported features:
+					// barBrowser: FeatureX, FeatureZ
+					// bazBrowser: FeatureX
+					// Missing in on for bazBrowser: FeatureZ
+					{
+						EventReleaseDate: time.Date(2024, 1, 25, 0, 0, 0, 0, time.UTC),
+						Count:            1,
+					},
+					// barBrowser 113 release
+					// Currently supported features:
+					// barBrowser: FeatureX, FeatureZ
+					// bazBrowser: None
+					// Missing in on for bazBrowser: FeatureX, FeatureZ
+					{
+						EventReleaseDate: time.Date(2024, 1, 20, 0, 0, 0, 0, time.UTC),
+						Count:            2,
+					},
+				},
+			}
+
+			assertListMissingOneImplCounts(
+				ctx,
+				t,
+				defaultStartAt,
+				defaultEndAt,
+				nil,
+				targetBrowser,
+				otherBrowsers,
+				defaultPageSize,
+				expectedResult,
+			)
+		})
+	})
+
+	// Misc tests just to make sure we can get other browser info.
+	// nolint:dupl // WONTFIX - false positive
+	t.Run("all fooBrowser data", func(t *testing.T) {
+		targetBrowser := "fooBrowser"
+		otherBrowsers := []string{
+			"barBrowser",
+			"bazBrowser",
+		}
+
+		expectedResult := &MissingOneImplCountPage{
+			NextPageToken: nil,
+			Metrics: []MissingOneImplCount{
+				// fooBrowser 113 release
+				// Currently supported features:
+				// fooBrowser: FeatureX, FeatureY, FeatureZ
+				// barBrowser: FeatureX, FeatureZ, FeatureY, FeatureW
+				// bazBrowser: FeatureX, FeatureY
+				// Missing in on for fooBrowser: None
+				{
+					EventReleaseDate: time.Date(2024, 4, 15, 0, 0, 0, 0, time.UTC),
+					Count:            0,
+				},
+				// barBrowser 115 AND bazBrowser 17 release
+				// Currently supported features:
+				// fooBrowser: FeatureX, FeatureY, FeatureZ
+				// barBrowser: FeatureX, FeatureZ, FeatureY, FeatureW
+				// bazBrowser: FeatureX, FeatureY
+				// Missing in on for fooBrowser: None
+				{
+					EventReleaseDate: time.Date(2024, 4, 1, 0, 0, 0, 0, time.UTC),
+					Count:            0,
+				},
+				// barBrowser 114 release
+				// Currently supported features:
+				// fooBrowser: FeatureX, FeatureY, FeatureZ
+				// barBrowser: FeatureX, FeatureZ, FeatureY
+				// bazBrowser: FeatureX, FeatureY
+				// Missing in on for fooBrowser: None
+				{
+					EventReleaseDate: time.Date(2024, 3, 28, 0, 0, 0, 0, time.UTC),
+					Count:            0,
+				},
+				// fooBrowser 112 release
+				// Currently supported features:
+				// fooBrowser: FeatureX, FeatureY, FeatureZ
+				// barBrowser: FeatureX, FeatureZ
+				// bazBrowser: FeatureX, FeatureY
+				// Missing in on for fooBrowser: None
+				{
+					EventReleaseDate: time.Date(2024, 3, 15, 0, 0, 0, 0, time.UTC),
+					Count:            0,
+				},
+				// bazBrowser 16.5 release
+				// Currently supported features:
+				// fooBrowser: FeatureX
+				// barBrowser: FeatureX, FeatureZ
+				// bazBrowser: FeatureX, FeatureY
+				// Missing in on for fooBrowser: None
+				{
+					EventReleaseDate: time.Date(2024, 3, 5, 0, 0, 0, 0, time.UTC),
+					Count:            0,
+				},
+				// fooBrowser 111 release
+				// Currently supported features:
+				// fooBrowser: FeatureX
+				// barBrowser: FeatureX, FeatureZ
+				// bazBrowser: FeatureX
+				// Missing in on for fooBrowser: None
+				{
+					EventReleaseDate: time.Date(2024, 2, 1, 0, 0, 0, 0, time.UTC),
+					Count:            0,
+				},
+				// bazBrowser 16.4  release
+				// Currently supported features:
+				// fooBrowser: None
+				// barBrowser: FeatureX, FeatureZ
+				// bazBrowser: FeatureX
+				// Missing in on for fooBrowser: FeatureX
+				{
+					EventReleaseDate: time.Date(2024, 1, 25, 0, 0, 0, 0, time.UTC),
+					Count:            1,
+				},
+				// barBrowser 113 release
+				// Currently supported features:
+				// fooBrowser: None
+				// barBrowser: FeatureX, FeatureZ
+				// bazBrowser: None
+				// Missing in on for fooBrowser: None
+				{
+					EventReleaseDate: time.Date(2024, 1, 20, 0, 0, 0, 0, time.UTC),
+					Count:            0,
+				},
+				// fooBrowser 110 release
+				// Currently supported features:
+				// fooBrowser: None
+				// barBrowser: None
+				// bazBrowser: None
+				// Missing in on for fooBrowser: None
+				{
+					EventReleaseDate: time.Date(2024, 1, 10, 0, 0, 0, 0, time.UTC),
+					Count:            0,
+				},
+			},
+		}
+
+		assertListMissingOneImplCounts(
+			ctx,
+			t,
+			defaultStartAt,
+			defaultEndAt,
+			nil,
+			targetBrowser,
+			otherBrowsers,
+			defaultPageSize,
+			expectedResult,
+		)
+	})
+}