[403] [DFN[[CODE(HTTP)[[[402]]]]]] ([DFN[[[Payment Required]]]]) は、[[課金]]に関する制限により[[要求]]が処理されなかったことを示す[[状態符号]]です。 * 仕様書 [REFS[ - [404] [CITE@en[RFC 7231 - Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content]] ([TIME[2014-08-07 05:54:02 +09:00]] 版) ]REFS] [405] 歴代の [[HTTP]] [[仕様書]]は [CODE(HTTP)[[[402]]]] を[[予約]]しているだけで、 実質的な定義は存在していません。 * 構文 [407] [[応答]]の [[payload body]] には、アクセス頻度や[[課金]]などに関するエラーであることを示す短い文章が含まれるのが普通です。 [408] アクセス状況や[[課金]]の状態などを[[機械可読]]な形で提示したり、 自動的に支払いを行ったりするような仕組みは存在していません。 * 文脈 [406] かつて [CODE(HTTP)[[[402]]]] [[応答]]は、 [[Web API]] に ([[鯖]]の判断基準による) 過剰なアクセスがあった場合にしばしば用いられていました。現在ではそうした場合は [CODE(HTTP)[[[429]]]] がより適切と考えられています。 * 歴史 [4] [[RFC 2068]], [[RFC 2616]], [[RFC 7231]] のいずれも、 [CODE(HTTP)[[[402]]]] ([CODE(HTTP)[[[Payment Required]]]]) は[[理由句]]が定義されているだけで、 [[状態符号]]自体は予約 [SRC[>>2, >>3]] されていて、使われていません。 [FIG(quote)[ [FIGCAPTION[ [2] RFC 2068 & 2616 (HTTP/1.1) 10.4.3 402 Payment Required ]FIGCAPTION] > This code is reserved for future use. この符号は将来の使用のために予約しています。 ]FIG] [REFS[ - [3] [CITE@en[RFC 7231 - Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content]] ([TIME[2014-08-07 05:54:02 +09:00]] 版) ]REFS] [REFS[ - [1] [CITE[法と技術とクローラと私 - 最速転職研究会]] ([TIME[2010-07-08 07:47:20 +09:00]] 版) ]REFS] [409] [CITE@en[RFC 2660 - The Secure HyperText Transfer Protocol]] ( ([TIME[2014-11-09 14:12:37 +09:00]] 版)) [FIG(quote)[ [FIGCAPTION[ [5] [CITE@en[REST API Reference - PayPal Developer]] ([TIME[2015-07-02 12:54:14 +09:00]] 版) ]FIGCAPTION] > 402 - Failed request ]FIG] [FIG(quote)[ [FIGCAPTION[ [6] [CITE@en[Stripe API Reference]] ([TIME[2015-08-29 17:37:34 +09:00]] 版) ]FIGCAPTION] > When a request is valid but does not complete successfully (e.g. a card is declined), we return a 402 error code. > 402 - Request Failed Parameters were valid but request failed. ]FIG] [FIG(quote)[ [FIGCAPTION[ [7] [CITE[402 Payment Requiredが出た方へ]] ( ([TIME[2012-02-11 05:45:34 +09:00]])) ]FIGCAPTION] > > 本サイトは同時接続数制限2ですので、それを超えるとエラーが出るようにしています。 ]FIG] [FIG(quote)[ [FIGCAPTION[ [8] [CITE@en[New HTTP Status Code (402 - Payment Required) - API Announcements — Ecommerce University]] ( ([TIME[2016-05-15 18:33:58 +09:00]])) ]FIGCAPTION] > I want to let you know the API will now respond with (402 - Payment Required) when a shop does not have access to a specific feature. Prior to this change the API would respond with (404 - Not Found). > In addition to this HTTP Status Code there will be an error included in the JSON response: > This shop's plan does not have access to this feature ]FIG] [FIG(quote)[ [FIGCAPTION[ [9] [CITE@en[Google APIs - Global domain errors  |  YouTube Data API  |  Google Developers]] ( ([TIME[2015-05-21 03:44:24 +09:00]])) ]FIGCAPTION] > dailyLimitExceeded402 A daily budget limit set by the developer has been reached. > quotaExceeded402 The requested operation requires more resources than the quota allows. Payment is required to complete the operation. > user402 The requested operation requires some kind of payment from the authenticated user. ]FIG] [10] [CITE@ja[XユーザーのCoinbase Developer Platform🛡️さん: 「First, a little history: HTTP 402 “Payment Required” has been a part of the internet’s blueprint for decades, but it was never used. x402 turns this 402 status code into a real payment layer—letting any server request payment, and any client (human or agent) respond with」 / X]], [TIME[午前1:04 · 2025年5月7日][2025-05-06T16:04:00.000Z]], [TIME[2025-05-08T02:48:50.000Z]] [11] [CITE@en[x402.org]], [TIME[2025-05-08T03:02:38.000Z]] [12] [CITE@ja[x402: The Payment Protocol for Agentic Commerce - x402-whitepaper.pdf]], [TIME[2025-05-08T01:20:16.000Z]], [TIME[2025-05-08T03:03:22.564Z]] [13] [CITE@en[GitHub - coinbase/x402: A payments protocol for the internet. Built on HTTP.]], [TIME[2025-05-08T03:04:39.000Z]] [14] [CITE@en[Introducing x402: a new standard for internet-native payments | Coinbase]], [TIME[2025-05-08T03:05:17.000Z]] [15] [CITE@en-us[Introducing pay per crawl: enabling content owners to charge AI crawlers for access]], [TIME[2025-07-03T02:31:59.000Z]]