Anthropic Claude Pro/Max OAuth login fails with 429 on token exchange

Description

opencode auth login -p anthropic -m "Claude Pro/Max" consistently fails during the OAuth code exchange step with 429 Too Many Requests from https://console.anthropic.com/v1/oauth/token.

This is not just a generic Failed to authorize UI problem; with local debug logging enabled in the Anthropic auth plugin, the underlying failure is:

[opencode-anthropic-auth] OAuth exchange failed: status=429 statusText=Too Many Requests headers={...} body={
  "error": {
    "type": "rate_limit_error",
    "message": "Rate limited. Please try again later."
  }
}

I can reproduce this across multiple Anthropic accounts, which makes it look more like a flow-level / client-level / IP-level throttle than an account-specific Max-plan problem.

Environment

OpenCode version: 1.2.20
OS: macOS
Provider: anthropic
Login method: Claude Pro/Max

Steps to reproduce

Run:

opencode auth login -p anthropic -m "Claude Pro/Max" --print-logs --log-level DEBUG

Open the provided claude.ai/oauth/authorize URL in the browser.
Complete login successfully in Claude.
Paste the returned authorization code back into OpenCode.
Observe Failed to authorize.

What is happening underneath

The browser authorization step succeeds and returns a code.

The failure happens on the follow-up token exchange to:

POST https://console.anthropic.com/v1/oauth/token

The plugin currently collapses that HTTP failure into a generic Failed to authorize message.

Related behavior

Earlier in the same session, Anthropic OAuth refresh was also failing for prompt traffic with:

Error: Token refresh failed: 429

So both fresh login and refresh appear to be failing on the Anthropic OAuth/token path.

Notes

Anthropic status page was nominal at the time.
We also tested changing the outgoing User-Agent for Anthropic requests locally, but the 429 still occurred.
The response did not include a Retry-After header or obvious Anthropic rate-limit reset metadata, only generic front-door headers.

Request

It would help a lot if OpenCode could:

Surface the real OAuth exchange status/body instead of only Failed to authorize.
Clarify whether this Anthropic OAuth flow is still supported / expected to work for Claude Pro/Max.
Potentially make the Anthropic auth/user-agent behavior configurable for debugging.

If helpful, I can provide the exact debug patch used to expose the hidden exchange error.

This issue might be a duplicate of existing issues. Please check:

Claude code 0auth broked!? #18267: Reports the same 429 error on Anthropic Claude Pro/Max OAuth token exchange
Claude Pro/Max auth flow returns Invalid token. #18315: Reports Claude Pro/Max auth flow failures (Invalid Token / Failed refresh token) — same auth flow
Repository anomalyco/opencode-anthropic-auth no longer exists, why? #18265: Related discussion about the Anthropic auth plugin being removed/unavailable

Please review those issues to see if your problem is already being tracked, and consider adding your findings there instead.

Wrote a user agent configuration plugin to solve this actually, it did end up working: https://github.com/dotCipher/opencode-anthropic-user-agent-plugin

Follow-up: I was able to work around this locally by changing the Anthropic-facing User-Agent, and that resolved the login issue for me.

So at least in my case, this does not appear to be a generic bad auth-code problem. It looks more like the Anthropic OAuth/token exchange path was sensitive to the client fingerprint / user-agent being sent by OpenCode on this flow.

What I observed:

claude.ai/oauth/authorize succeeded
the failure was on POST https://console.anthropic.com/v1/oauth/token
after overriding the Anthropic-facing User-Agent, the flow started working

I packaged the workaround as a small OpenCode plugin here:

This may help narrow the root cause:

OpenCode's Anthropic auth flow may be sending a User-Agent that triggers throttling / rejection on Anthropic's token exchange path.
It may be worth making the Anthropic User-Agent configurable for debugging.
It would still be helpful for OpenCode to surface the real exchange response instead of only Failed to authorize.

not work for me. btw the oAuth domain has changed to platform.anthropic.com

I tried your user-agent plugin first — thanks for the detailed root cause analysis. In my case the OAuth flow itself was broken regardless of UA, so I took a different approach: syncing existing Claude CLI credentials directly into OpenCode's auth store, skipping the OAuth login entirely.

Not an npm package — plain shell scripts (~100 lines) you can audit before running. No supply chain risk.

Repo: https://github.com/lehdqlsl/opencode-claude-auth-sync

here's the fix https://github.com/vinzabe/opencode-anthropic-oauth-fix

I'm not sure this will be fixed :/
#18186

Tested a working workaround on macOS with OpenCode 1.2.27 and Claude Code 2.1.80.

This does not fix the built-in Anthropic login flow itself, but it did restore Anthropic usage end-to-end here:

Remove local Anthropic patches/plugins from OpenCode (custom auth plugins, user-agent overrides, prompt spoof plugins).
Remove the stale Anthropic entry from OpenCode auth storage.
Re-auth Claude CLI with claude auth login --claudeai.
Sync Claude CLI credentials into OpenCode using opencode-claude-auth-sync:
https://github.com/lehdqlsl/opencode-claude-auth-sync
Verify the sync script reports a valid token before testing OpenCode.

Important detail: if the sync script reports EXPIRED, syncing will not help. Refresh Claude CLI first, then sync again.

After doing that, this worked:

opencode run --model anthropic/claude-sonnet-4-0 "Reply only with OK"

Result:

OK

So the reliable workaround for me was: use Claude CLI as the source of truth for Anthropic OAuth, then sync those fresh credentials into OpenCode instead of relying on OpenCode's Anthropic login flow.

@nichochar

Fix Available

The root cause of this 429 on token exchange has been identified and fixed in the opencode-anthropic-auth plugin:

Two issues in opencode-anthropic-auth v0.0.13:

Wrong Content-Type: Token exchange and refresh requests use application/json with JSON.stringify(), but Anthropic's /v1/oauth/token endpoint expects application/x-www-form-urlencoded (per OAuth 2.0 RFC 6749 §4.1.3).
Missing User-Agent header (primary cause of 429): The plugin sets User-Agent: claude-cli/2.1.2 (external, cli) for API calls but omits it from token exchange/refresh requests. Anthropic's token endpoint rate-limits requests that don't match the expected Claude CLI request shape.

PR with fix: ex-machina-co/opencode-anthropic-auth#12

After applying both changes, opencode auth login → Anthropic → Claude Pro/Max successfully obtains tokens and Claude models work correctly.

cc @nichochar @julian-opencode

https://github.com/vinzabe/opencode-anthropic-oauth-fix

it doesn't work

This is not an error ! Claude his blocking opencode now for legal reason se PR : #18186
What a shame ....

I just canceled my subscrption to claude and i m now switching to ChatGPT Plus !

Update: OpenCode has officially dropped Claude support

Hi everyone — I want to provide an important update to clarify the situation here, as there seem to be many workarounds being shared that may no longer be relevant.

On March 20, 2026, Dax (OpenCode lead) announced on X that OpenCode is officially removing Claude OAuth support, following a formal legal request from Anthropic. The relevant commit is titled "Anthropic legal requests" and redirects users to alternative providers (OpenAI, GitHub, GitLab, etc.).

What this means

The 429 errors on token exchange were not a bug — they were Anthropic deliberately rate-limiting third-party OAuth clients at the token endpoint level
Anthropic's updated ToS (February 2026) explicitly prohibits using Claude Free/Pro/Max OAuth tokens outside of Claude Code and claude.ai
My earlier PR (fix: use form-urlencoded and Claude CLI User-Agent for OAuth token requests ex-machina-co/opencode-anthropic-auth#12) addressed a real technical issue (wrong Content-Type + missing User-Agent), and it did make login succeed temporarily — but the underlying policy decision from Anthropic means this is not a sustainable path forward

For those still looking for solutions

Anthropic API keys (pay-per-token) still work with OpenCode — this is the only officially supported method
OpenAI, Google, GitHub Copilot OAuth remain fully functional alternatives within OpenCode
Credential sync workarounds may work today but carry ToS violation risk

I'm closing my PR accordingly. Thank you to everyone who helped investigate this issue.

Quick update on my workaround repo (opencode-claude-auth-sync): I shipped v0.3.1 to clarify and fix the refresh semantics.

Claude CLI does not proactively rotate tokens just because they are near expiry; it refreshes once the token is actually expired/unusable. The repo/docs now match that verified behavior.

Upgrade:

curl -fsSL https://raw.githubusercontent.com/lehdqlsl/opencode-claude-auth-sync/main/install.sh | bash

Release: https://github.com/lehdqlsl/opencode-claude-auth-sync/releases/tag/v0.3.1

@g14wx

@g14wx The 429 on token exchange means you're on an older version that used the wrong User-Agent.

Update to the latest:

npm install -g opencode-anthropic-oauth@latest

Verify you're on v0.3.0:

npm list -g opencode-anthropic-oauth

Add to your opencode.json:

{
  "plugin": ["opencode-anthropic-oauth@latest"]
}

Then clear OpenCode's plugin cache and retry:

rm -rf ~/.cache/opencode/node_modules/opencode-anthropic-oauth
oc auth login

v0.3.0 uses the correct User-Agent: claude-cli/2.1.80 on the token exchange — the old versions used User-Agent: anthropic which Anthropic blanket-rejects with 429.

@g14wx The 429 on token exchange means you're on an older version that used the wrong User-Agent.

Update to the latest:

npm install -g opencode-anthropic-oauth@latest
Verify you're on v0.3.0:

npm list -g opencode-anthropic-oauth
Add to your opencode.json:
{
  "plugin": ["opencode-anthropic-oauth@latest"]
}
Then clear OpenCode's plugin cache and retry:

rm -rf ~/.cache/opencode/node_modules/opencode-anthropic-oauth
oc auth login
v0.3.0 uses the correct User-Agent: claude-cli/2.1.80 on the token exchange — the old versions used User-Agent: anthropic which Anthropic blanket-rejects with 429.

king. share your donate link!

here's the permanent fix - https://github.com/vinzabe/PERMANENT-opencode-anthropic-oauth-fix

fix: dynamic OAuth User-Agent detection and curl-based token endpoints

fix: dynamic OAuth User-Agent detection and curl-based token endpoints (

@shahidshabbir-se

Wow seriously thanks a lot @shahidshabbir-se , what a detailed solution

thank you so much!

For anyone still hitting OAuth issues with Anthropic, I built opencode-claude-bridge which combines fixes from several community plugins into one. It auto-syncs tokens from Claude CLI's keychain (zero-click if you're already logged in), handles token refresh, and emulates Claude Code's exact request format. Install: just add "plugin": ["opencode-claude-bridge"] to your OpenCode config — it auto-installs from npm.

For anyone still hitting OAuth issues with Anthropic, I built opencode-claude-bridge which combines fixes from several community plugins into one. It auto-syncs tokens from Claude CLI's keychain (zero-click if you're already logged in), handles token refresh, and emulates Claude Code's exact request format. Install: just add "plugin": ["opencode-claude-bridge"] to your OpenCode config — it auto-installs from npm.

On opencode 1.3 i have this error "Anthropic API key is missing. Pass it using the 'apiKey' parameter or the ANTHROPIC_API_KEY environment variable."

@mateusz28011

@mateusz28011 file an issue on my project if you have problems and I'll look into them on a case-by-case basis

I had the same issue.

@mateusz28011

Update for OpenCode 1.3+ — opencode-claude-bridge v1.6.1

For those still hitting issues (especially after the OpenCode 1.3 update that removed the built-in Anthropic plugin), I've released v1.6.1 of opencode-claude-bridge with several fixes:

What was breaking on OpenCode 1.3:

The removal of the built-in Anthropic provider meant that OAuth requests were no longer automatically injecting a required x-anthropic-billing-header system block — Anthropic's API silently rejects these requests without it
Some users saw "Anthropic API key is missing" because the SDK required a non-empty key at initialization time even during OAuth flows
Model selection could break if the plugin's auth loader threw during provider initialization

What v1.6.1 fixes:

Injects the x-anthropic-billing-header system block automatically (required for OAuth on OpenCode 1.3)
Sets a placeholder ANTHROPIC_API_KEY instead of deleting it, so the SDK initializes cleanly — the real Authorization: Bearer token is set in the request headers by the fetch wrapper
Guards provider.models access in case OpenCode 1.3 passes an incomplete provider object during model selection

Install / upgrade:

{ "plugin": ["opencode-claude-bridge"] }

Or upgrade manually:

cd ~/.cache/opencode && npm install opencode-claude-bridge@latest

Then restart OpenCode. If you're logged into Claude CLI (claude login), it auto-syncs your credentials — no re-auth needed.

@mateusz28011 and @skhaz — the "API key missing" error should be resolved in v1.6.1.

brew upgrade opencode :)

Closing, as this is not supported directly by opencode anymore, see thread: #18267

I wrote a plugin for opencode to support my use case, released here: https://github.com/dotCipher/opencode-claude-bridge

Default Avante to Copilot; run Claude via Claude Code CLI instead

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Anthropic Claude Pro/Max OAuth login fails with 429 on token exchange #18329

Description

Environment

Steps to reproduce

What is happening underneath

Related behavior

Notes

Request

Fix Available

Update: OpenCode has officially dropped Claude support

What this means

For those still looking for solutions

5 remaining items

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Anthropic Claude Pro/Max OAuth login fails with 429 on token exchange #18329

Description

Description

Environment

Steps to reproduce

What is happening underneath

Related behavior

Notes

Request

Activity

github-actions commented on Mar 20, 2026

dotCipher commented on Mar 20, 2026

dotCipher commented on Mar 20, 2026

Nick-Hopps commented on Mar 20, 2026

lehdqlsl commented on Mar 20, 2026

vinzabe commented on Mar 20, 2026

DerDummePunkt commented on Mar 20, 2026

JlMoreno00 commented on Mar 20, 2026

MoerAI commented on Mar 20, 2026

Fix Available

ultism commented on Mar 20, 2026

ggi-svg commented on Mar 20, 2026

MoerAI commented on Mar 20, 2026

Update: OpenCode has officially dropped Claude support

What this means

For those still looking for solutions

lehdqlsl commented on Mar 20, 2026

5 remaining items

shahidshabbir-se commented on Mar 21, 2026

ErcinDedeoglu commented on Mar 21, 2026

vinzabe commented on Mar 21, 2026

g14wx commented on Mar 21, 2026

dotCipher commented on Mar 23, 2026

mateusz28011 commented on Mar 23, 2026

dotCipher commented on Mar 23, 2026

skhaz commented on Mar 23, 2026

dotCipher commented on Mar 23, 2026

Sleepful commented on Mar 31, 2026

dotCipher commented on Apr 16, 2026

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