diff --git a/tariff/ostrom.go b/tariff/ostrom.go
new file mode 100644
index 0000000000..fdfd9e630b
--- /dev/null
+++ b/tariff/ostrom.go
@@ -0,0 +1,265 @@
+package tariff
+
+import (
+	"errors"
+	"fmt"
+	"net/http"
+	"net/url"
+	"slices"
+	"strings"
+	"sync"
+	"time"
+
+	"github.com/cenkalti/backoff/v4"
+	"github.com/evcc-io/evcc/api"
+	"github.com/evcc-io/evcc/tariff/ostrom"
+	"github.com/evcc-io/evcc/util"
+	"github.com/evcc-io/evcc/util/oauth"
+	"github.com/evcc-io/evcc/util/request"
+	"github.com/evcc-io/evcc/util/transport"
+	"github.com/jinzhu/now"
+	"golang.org/x/oauth2"
+)
+
+type Ostrom struct {
+	*embed
+	*request.Helper
+	log          *util.Logger
+	zip          string
+	contractType string
+	cityId       int // Required for the Fair tariff types
+	basic        string
+	data         *util.Monitor[api.Rates]
+}
+
+var _ api.Tariff = (*Ostrom)(nil)
+
+func init() {
+	registry.Add("ostrom", NewOstromFromConfig)
+}
+
+// Search for a contract in list of contracts
+func ensureContractEx(cid int64, contracts []ostrom.Contract) (ostrom.Contract, error) {
+	var zero ostrom.Contract
+
+	if cid != -1 {
+		// cid defined
+		for _, contract := range contracts {
+			if cid == contract.Id {
+				return contract, nil
+			}
+		}
+	} else if len(contracts) == 1 {
+		// cid empty and exactly one object
+		return contracts[0], nil
+	}
+
+	return zero, errors.New("cannot find contract")
+}
+
+func NewOstromFromConfig(other map[string]interface{}) (api.Tariff, error) {
+	var cc struct {
+		ClientId     string
+		ClientSecret string
+		Contract     int64
+	}
+
+	cc.Contract = -1
+	if err := util.DecodeOther(other, &cc); err != nil {
+		return nil, err
+	}
+
+	if cc.ClientId == "" || cc.ClientSecret == "" {
+		return nil, api.ErrMissingCredentials
+	}
+
+	basic := transport.BasicAuthHeader(cc.ClientId, cc.ClientSecret)
+	log := util.NewLogger("ostrom").Redact(basic)
+
+	t := &Ostrom{
+		log:    log,
+		basic:  basic,
+		Helper: request.NewHelper(log),
+		data:   util.NewMonitor[api.Rates](2 * time.Hour),
+	}
+
+	t.Client.Transport = &oauth2.Transport{
+		Base:   t.Client.Transport,
+		Source: oauth.RefreshTokenSource(nil, t),
+	}
+
+	contracts, err := t.getContracts()
+	if err != nil {
+		return nil, err
+	}
+	contract, err := ensureContractEx(cc.Contract, contracts)
+	if err != nil {
+		return nil, err
+	}
+
+	t.contractType = contract.Product
+	t.zip = contract.Address.Zip
+
+	done := make(chan error)
+	if t.Type() == api.TariffTypePriceStatic {
+		t.cityId, err = t.getCityId()
+		if err != nil {
+			return nil, err
+		}
+		go t.runStatic(done)
+	} else {
+		go t.run(done)
+	}
+	err = <-done
+
+	return t, err
+}
+
+func (t *Ostrom) getContracts() ([]ostrom.Contract, error) {
+	var res ostrom.Contracts
+
+	uri := ostrom.URI_API + "/contracts"
+	err := t.GetJSON(uri, &res)
+	return res.Data, err
+}
+
+func (t *Ostrom) getCityId() (int, error) {
+	var city ostrom.CityId
+
+	uri := fmt.Sprintf("%s?zip=%s", ostrom.URI_GET_CITYID, t.zip)
+	if err := t.GetJSON(uri, &city); err != nil {
+		return 0, err
+	}
+	if len(city) < 1 {
+		return 0, errors.New("city not found")
+	}
+	return city[0].Id, nil
+}
+
+func (t *Ostrom) getFixedPrice() (float64, error) {
+	var tariffs ostrom.Tariffs
+
+	uri := fmt.Sprintf("%s?usage=1000&cityId=%d", ostrom.URI_GET_STATIC_PRICE, t.cityId)
+	if err := backoff.Retry(func() error {
+		return backoffPermanentError(t.GetJSON(uri, &tariffs))
+	}, bo()); err != nil {
+		return 0, err
+	}
+
+	for _, tariff := range tariffs.Ostrom {
+		if tariff.ProductCode == ostrom.PRODUCT_BASIC {
+			return tariff.UnitPricePerkWH, nil
+		}
+	}
+
+	return 0, errors.New("tariff not found")
+}
+
+func (t *Ostrom) RefreshToken(_ *oauth2.Token) (*oauth2.Token, error) {
+	uri := ostrom.URI_AUTH + "/oauth2/token"
+	data := url.Values{"grant_type": {"client_credentials"}}
+	req, _ := request.New(http.MethodPost, uri, strings.NewReader(data.Encode()), map[string]string{
+		"Authorization": t.basic,
+		"Content-Type":  request.FormContent,
+		"Accept":        request.JSONContent,
+	})
+
+	var res oauth2.Token
+	client := request.NewHelper(t.log)
+	err := client.DoJSON(req, &res)
+	return util.TokenWithExpiry(&res), err
+}
+
+// This function is used to calculate the prices for the Simplay Fair tarrifs
+// using the price given in the configuration
+// Unfortunately, the API does not allow to query the price for these yet.
+func (t *Ostrom) runStatic(done chan error) {
+	var once sync.Once
+
+	tick := time.NewTicker(time.Hour)
+	for ; true; <-tick.C {
+		price, err := t.getFixedPrice()
+		if err != nil {
+			once.Do(func() { done <- err })
+			t.log.ERROR.Println(err)
+			continue
+		}
+
+		data := make(api.Rates, 48)
+		for i := range data {
+			ts := now.BeginningOfDay().Add(time.Duration(i) * time.Hour)
+			data[i] = api.Rate{
+				Start: ts,
+				End:   ts.Add(time.Hour),
+				Price: price / 100.0,
+			}
+		}
+
+		mergeRates(t.data, data)
+		once.Do(func() { close(done) })
+	}
+}
+
+// This function calls th ostrom API to query the
+// dynamic prices
+func (t *Ostrom) run(done chan error) {
+	var once sync.Once
+
+	tick := time.NewTicker(time.Hour)
+	for ; true; <-tick.C {
+		var res ostrom.Prices
+
+		start := now.BeginningOfDay()
+		end := start.AddDate(0, 0, 2)
+
+		params := url.Values{
+			"startDate":  {start.Format(time.RFC3339)},
+			"endDate":    {end.Format(time.RFC3339)},
+			"resolution": {"HOUR"},
+			"zip":        {t.zip},
+		}
+
+		uri := fmt.Sprintf("%s/spot-prices?%s", ostrom.URI_API, params.Encode())
+		if err := backoff.Retry(func() error {
+			return backoffPermanentError(t.GetJSON(uri, &res))
+		}, bo()); err != nil {
+			once.Do(func() { done <- err })
+			t.log.ERROR.Println(err)
+			continue
+		}
+
+		data := make(api.Rates, 0, 48)
+		for _, val := range res.Data {
+			ts := val.StartTimestamp.Local()
+			data = append(data, api.Rate{
+				Start: ts,
+				End:   ts.Add(time.Hour),
+				Price: (val.Marketprice + val.AdditionalCost) / 100.0, // Both values include VAT
+			})
+		}
+
+		mergeRates(t.data, data)
+		once.Do(func() { close(done) })
+	}
+}
+
+// Rates implements the api.Tariff interface
+func (t *Ostrom) Rates() (api.Rates, error) {
+	var res api.Rates
+	err := t.data.GetFunc(func(val api.Rates) {
+		res = slices.Clone(val)
+	})
+	return res, err
+}
+
+// Type implements the api.Tariff interface
+func (t *Ostrom) Type() api.TariffType {
+	switch t.contractType {
+	case ostrom.PRODUCT_DYNAMIC:
+		return api.TariffTypePriceForecast
+	case ostrom.PRODUCT_FAIR, ostrom.PRODUCT_FAIR_CAP:
+		return api.TariffTypePriceStatic
+	default:
+		panic("invalid contract type: " + t.contractType)
+	}
+}
diff --git a/tariff/ostrom/api.go b/tariff/ostrom/api.go
new file mode 100644
index 0000000000..a56cf3f36e
--- /dev/null
+++ b/tariff/ostrom/api.go
@@ -0,0 +1,95 @@
+package ostrom
+
+import (
+	"time"
+)
+
+// URIs, production and sandbox
+// see https://docs.ostrom-api.io/reference/environments
+
+const (
+	URI_AUTH_PRODUCTION  = "https://auth.production.ostrom-api.io"
+	URI_API_PRODUCTION   = "https://production.ostrom-api.io"
+	URI_AUTH_SANDBOX     = "https://auth.sandbox.ostrom-api.io"
+	URI_API_SANDBOX      = "https://sandbox.ostrom-api.io"
+	URI_GET_CITYID       = "https://api.ostrom.de/v1/addresses/cities"
+	URI_GET_STATIC_PRICE = "https://api.ostrom.de/v1/tariffs/city-id"
+	URI_AUTH             = URI_AUTH_PRODUCTION
+	URI_API              = URI_API_PRODUCTION
+)
+
+const (
+	PRODUCT_FAIR     = "SIMPLY_FAIR"
+	PRODUCT_FAIR_CAP = "SIMPLY_FAIR_WITH_PRICE_CAP"
+	PRODUCT_DYNAMIC  = "SIMPLY_DYNAMIC"
+	PRODUCT_BASIC    = "basisProdukt"
+)
+
+type Prices struct {
+	Data []ForecastInfo
+}
+
+type ForecastInfo struct {
+	StartTimestamp time.Time `json:"date"`
+	Marketprice    float64   `json:"grossKwhPrice"`
+	AdditionalCost float64   `json:"grossKwhTaxAndLevies"`
+}
+
+type Contracts struct {
+	Data []Contract
+}
+
+type Address struct {
+	Zip         string `json:"zip"`         //"22083",
+	City        string `json:"city"`        //"Hamburg",
+	Street      string `json:"street"`      //"Mozartstr.",
+	HouseNumber string `json:"housenumber"` //"35"
+}
+
+type Contract struct {
+	Id        int64   `json:"id"`                          //"100523456",
+	Type      string  `json:"type"`                        //"ELECTRICITY",
+	Product   string  `json:"productCode"`                 //"SIMPLY_DYNAMIC",
+	Status    string  `json:"status"`                      //"ACTIVE",
+	FirstName string  `json:"customerFirstName"`           //"Max",
+	LastName  string  `json:"customerLastName"`            //"Mustermann",
+	StartDate string  `json:"startDate"`                   // "2024-03-22",
+	Dposit    int     `json:"currentMonthlyDepositAmount"` //120,
+	Address   Address `json:"address"`
+}
+
+type CityId []struct {
+	Id       int    `json:"id"`
+	Postcode string `json:"postcode"`
+	Name     string `json:"name"`
+}
+
+type Tariffs struct {
+	Ostrom []struct {
+		ProductCode                              string  `json:"productCode"`
+		Tariff                                   int     `json:"tariff"`
+		BasicFee                                 int     `json:"basicFee"`
+		NetworkFee                               float64 `json:"networkFee"`
+		UnitPricePerkWH                          float64 `json:"unitPricePerkWH"`
+		TariffWithStormPreisBremse               int     `json:"tariffWithStormPreisBremse"`
+		StromPreisBremseUnitPrice                int     `json:"stromPreisBremseUnitPrice"`
+		AccumulatedUnitPriceWithStromPreisBremse float64 `json:"accumulatedUnitPriceWithStromPreisBremse"`
+		UnitPrice                                float64 `json:"unitPrice"`
+		EnergyConsumption                        int     `json:"energyConsumption"`
+		BasePriceBrutto                          float64 `json:"basePriceBrutto"`
+		WorkingPriceBrutto                       float64 `json:"workingPriceBrutto"`
+		WorkingPriceNetto                        float64 `json:"workingPriceNetto"`
+		MeterChargeBrutto                        int     `json:"meterChargeBrutto"`
+		WorkingPricePowerTax                     float64 `json:"workingPricePowerTax"`
+		AverageHourlyPriceToday                  float64 `json:"averageHourlyPriceToday,omitempty"`
+		MinHourlyPriceToday                      float64 `json:"minHourlyPriceToday,omitempty"`
+		MaxHourlyPriceToday                      float64 `json:"maxHourlyPriceToday,omitempty"`
+	} `json:"ostrom"`
+	Footprint struct {
+		Usage          int `json:"usage"`
+		KgCO2Emissions int `json:"kgCO2Emissions"`
+	} `json:"footprint"`
+	IsPendingApplicationAllowed bool   `json:"isPendingApplicationAllowed"`
+	Status                      string `json:"status"`
+	PartnerName                 any    `json:"partnerName"`
+}
diff --git a/templates/definition/tariff/ostrom.yaml b/templates/definition/tariff/ostrom.yaml
new file mode 100644
index 0000000000..834780eb2c
--- /dev/null
+++ b/templates/definition/tariff/ostrom.yaml
@@ -0,0 +1,26 @@
+template: ostrom
+products:
+  - brand: Ostrom
+requirements:
+  description:
+    en: "Create a 'Production Client' in the Ostrom developer portal: https://developer.ostrom-api.io/"
+    de: "Erzeuge einen 'Production Client' in dem Tibber-Entwicklerportal: https://developer.ostrom-api.io/"
+  evcc: ["skiptest"]
+group: price
+params:
+  - name: clientid
+    example: 476c477d8a039529478ebd690d35ddd80e3308ffc49b59c65b142321aee963a4
+    required: true
+  - name: clientsecret
+    example: 476c477d8a039529478ebd690d35ddd80e3308ffc49b59c65b142321aee963a4476c477d8a039529478ebd690d35ddd80e3308ffc49b59c65b142321aee963a4a
+    required: true
+  - name: contract
+    example: 100523456
+    help:
+      de: Nur erforderlich, wenn mehrere Verträge unter einem Benutzer existieren
+      en: Only required if multiple contracts belong to the same user
+render: |
+  type: ostrom
+  ClientId: {{ .clientid }}
+  ClientSecret: {{ .clientsecret }}
+  Contract: {{ .contract }}